U.S. patent number 6,390,869 [Application Number 09/794,240] was granted by the patent office on 2002-05-21 for four stroke engine with valve train arrangement.
This patent grant is currently assigned to Bombardier-Rotax GmbH. Invention is credited to Norbert Korenjak, Rudolf Kusel, Rudolf Tscherne, Alois Wolfsgruber.
United States Patent |
6,390,869 |
Korenjak , et al. |
May 21, 2002 |
Four stroke engine with valve train arrangement
Abstract
A four stroke internal combustion engine includes a cylinder
head having a valve train having reduced profile that permits
access to a spark plug assembly located therein.
Inventors: |
Korenjak; Norbert (Stadl Paura,
AT), Tscherne; Rudolf (Buchkirchen, AT),
Wolfsgruber; Alois (Gmunden, AT), Kusel; Rudolf
(Thalheim bei Weis, AT) |
Assignee: |
Bombardier-Rotax GmbH
(Gunskirchen, AT)
|
Family
ID: |
26881381 |
Appl.
No.: |
09/794,240 |
Filed: |
February 28, 2001 |
Current U.S.
Class: |
440/88R; 440/88A;
123/90.23 |
Current CPC
Class: |
F02B
67/04 (20130101); F01N 3/043 (20130101); F02B
77/085 (20130101); F01L 1/022 (20130101); F01L
1/181 (20130101); F02M 35/10072 (20130101); F02M
35/10216 (20130101); F02F 1/242 (20130101); F02B
33/44 (20130101); F02B 39/04 (20130101); F01L
1/053 (20130101); F02M 35/167 (20130101); F01L
1/18 (20130101); F01M 13/04 (20130101); F02M
35/10039 (20130101); F02M 35/10163 (20130101); F02M
35/10268 (20130101); F01N 13/02 (20130101); F02M
35/10275 (20130101); F02B 61/04 (20130101); F02B
61/045 (20130101); F02F 1/4214 (20130101); F02M
69/465 (20130101); F02M 35/10144 (20130101); F02B
67/10 (20130101); F16H 9/12 (20130101); F02B
33/40 (20130101); F02B 75/224 (20130101); F02B
75/16 (20130101); F02F 1/243 (20130101); F02M
35/112 (20130101); F01L 1/024 (20130101); F02B
33/34 (20130101); F01M 11/02 (20130101); F02B
75/20 (20130101); F02M 35/10111 (20130101); F02B
33/26 (20130101); F02B 75/22 (20130101); F02F
7/0031 (20130101); F01B 1/12 (20130101); F01L
1/02 (20130101); F01L 1/26 (20130101); F01P
3/02 (20130101); F16H 7/0848 (20130101); F01M
1/08 (20130101); F01L 1/2411 (20130101); F02M
35/10032 (20130101); F02M 35/10222 (20130101); F02B
67/06 (20130101); F02B 61/02 (20130101); F16H
55/563 (20130101); F01N 3/046 (20130101); F01N
13/004 (20130101); F16H 55/56 (20130101); F02B
39/14 (20130101); F02M 35/116 (20130101); F01L
1/245 (20130101); F01P 9/00 (20130101); F02B
67/00 (20130101); F02M 69/462 (20130101); Y02T
10/14 (20130101); F02B 2075/1812 (20130101); F02B
2275/18 (20130101); Y02T 10/12 (20130101); F02B
2275/08 (20130101); F01P 2060/04 (20130101); F01M
2011/0033 (20130101); Y02T 10/144 (20130101); F02B
2075/027 (20130101); F16H 2007/0806 (20130101); F01M
2001/126 (20130101); F01N 2590/022 (20130101); F01P
2050/06 (20130101); F05C 2201/021 (20130101); F01M
2011/002 (20130101); F02B 63/04 (20130101); Y02T
10/20 (20130101); F01L 2001/0535 (20130101); F02B
1/04 (20130101); F01P 2060/16 (20130101); F02B
2075/1808 (20130101); F16H 61/662 (20130101); F01M
2011/0066 (20130101); F01N 3/04 (20130101); F16H
2007/0812 (20130101); F01L 2301/00 (20200501); F01L
2305/00 (20200501); F01P 2050/04 (20130101); F01P
3/20 (20130101); F02B 2275/20 (20130101); F16H
2007/0859 (20130101); F01P 2050/02 (20130101); F01M
2013/0427 (20130101); F02F 2001/245 (20130101) |
Current International
Class: |
F01B
1/00 (20060101); F02B 75/20 (20060101); F01P
3/02 (20060101); F01N 7/00 (20060101); F01N
7/02 (20060101); F02B 75/16 (20060101); F01L
1/02 (20060101); F02B 33/26 (20060101); F01L
1/18 (20060101); F02M 69/46 (20060101); F02B
33/02 (20060101); F02F 1/24 (20060101); F02B
39/14 (20060101); F02B 33/44 (20060101); F02F
7/00 (20060101); F02B 39/00 (20060101); F01L
1/26 (20060101); F01L 1/24 (20060101); F02B
75/22 (20060101); F01L 1/053 (20060101); F02B
75/00 (20060101); F01P 9/00 (20060101); F01L
1/245 (20060101); F01L 1/04 (20060101); F01L
1/20 (20060101); F02B 67/00 (20060101); F01B
1/12 (20060101); F02B 67/04 (20060101); F02B
61/00 (20060101); F02B 67/06 (20060101); F02B
39/02 (20060101); F02B 33/40 (20060101); F02B
39/04 (20060101); F02B 67/10 (20060101); F02B
63/04 (20060101); F02B 63/00 (20060101); F02B
61/04 (20060101); F02B 33/34 (20060101); F02B
33/00 (20060101); F02M 35/00 (20060101); F02M
35/16 (20060101); F02M 35/104 (20060101); F01N
3/04 (20060101); F16H 7/08 (20060101); F02F
1/42 (20060101); F02M 35/10 (20060101); F01M
13/04 (20060101); F01M 13/00 (20060101); F02B
75/02 (20060101); F01P 3/20 (20060101); F02B
75/18 (20060101); F02B 1/00 (20060101); F02B
1/04 (20060101); F01M 11/00 (20060101); B63H
021/10 () |
Field of
Search: |
;440/38,88,89,84,900
;123/73AD,317,432,90.23,90.44,196W |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
23 33 688 |
|
Jan 1975 |
|
DE |
|
38 16 864 |
|
Nov 1989 |
|
DE |
|
39 12 487 |
|
Apr 1990 |
|
DE |
|
0 495 221 |
|
Jul 1992 |
|
EP |
|
WO 90/10145 |
|
Sep 1990 |
|
WO |
|
Other References
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|
Primary Examiner: Avila; Stephen
Attorney, Agent or Firm: Pillsbury Winthrop LLP
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This application relates to and claims priority on U.S. Provisional
Application No. 60/185,703, filed on Feb. 29, 2000, and U.S.
Provisional Application No. 60/257,174, filed on Dec. 22, 2000,
which are incorporated by reference herein.
Claims
What is claimed is:
1. A four stroke internal combustion engine, comprising:
a crankcase having a crank shaft rotatably mounted therein;
a cylinder head connected to the crankcase, wherein the crankcase
and the cylinder head form at least one cylinder;
at least one intake valve for the at least one cylinder, wherein
the at least one intake valve has an intake valve axis;
at least one exhaust valve for the at least one cylinder, wherein
the at least one exhaust valve has an exhaust valve axis;
a valve actuation assembly located in the cylinder head for
operating the at least one intake valve and the at least one
exhaust valve, wherein the valve actuation assembly is located
substantially between the intake valve axis and the exhaust valve
axis, the valve actuation assembly comprising
a cam shaft rotatably mounted within the cylinder head,
a support axle mounted within the cylinder head, offset from the
cam shaft;
at least one exhaust rocker arm pivotally mounted on the support
axle,
at least one intake rocker arm pivotally mounted on the support
axle,
wherein the cam shaft is operatively coupled to the crankshaft such
that rotational movement of the crankshaft is transferred to the
cam shaft,
wherein the at least one exhaust rocker arm is operatively coupled
to the cam shaft for operating the at least one exhaust valve,
and
wherein the at least one intake rocker arm is operatively coupled
to the cam shaft for operating the at least one intake valve;
and
a lubrication system for lubricating the engine,
wherein the lubrication system includes a supply of lubricant to
the cylinder head,
wherein the support axle has a central passageway extending
therethrough, and
wherein at least a portion of the supply of lubricant flows through
the central passageway in the support axle.
2. The four stroke internal combustion engine according to claim 1,
wherein each cylinder has a longitudinal axis, wherein each of the
at least one intake valve and the at least one exhaust valve is
disposed at an angle with respect to the longitudinal axis.
3. The four stroke internal combustion engine according to claim 2,
wherein the engine includes a pair of exhaust valves for each
cylinder and the valve actuation assembly includes an exhaust
rocker arm for each exhaust valve.
4. The four stroke internal combustion engine according to claim 3,
wherein each exhaust rocker arm comprises:
a cam follower located on one end of the exhaust rocker arm,
wherein the cam follower is adapted to follow a profile of an
exhaust cam lobe located on the camshaft; and
an exhaust hydraulic adjuster located on an opposite end of the
exhaust rocker arm, wherein the exhaust hydraulic adjuster is
adapted to contact and operate the exhaust valve in response to
movement of the exhaust rocker arm by the exhaust cam lobe.
5. The four stroke internal combustion engine according to claim 2,
wherein the engine includes a pair of intake valves for each
cylinder and the valve actuation assembly includes a forked intake
rocker arm for the pair of intake valves.
6. The four stroke internal combustion engine according to claim 5,
wherein the forked intake rocker arm comprises:
a cam follower located on one end of the intake rocker arm, wherein
the cam follower is adapted to follow a profile of an intake cam
lobe located on the camshaft;
a first actuator arm for operating a first of the pair of intake
valves;
a second actuator arm for operating a second of the pair of intake
valves; and
a pair of intake hydraulic adjusters located on an opposite end of
the forked intake rocker arm,
wherein each intake hydraulic adjuster is adapted to contact and
operate the one of the pair of intake valves in response to
movement of the intake rocker arm by the intake cam lobe.
7. The four stroke internal combustion engine according to claim 6,
wherein each of the intake hydraulic adjusters comprises:
an intake piston actuator slidably received within a cavity in an
end of the actuator arm, and a fluid passageway extending through
the actuator arm to the support axle, and
wherein the central passageway in the support axle is in fluidic
communication with the fluid passageway such that fluid within the
central passageway flows through the fluid passageway to the cavity
to bias the intake piston actuator into engagement with the intake
valve.
8. The four stroke internal combustion engine according to claim 7,
wherein the exhaust rocker arms are rotatably mounted on the
support axle on opposite sides of the intake rocker arm.
9. The four stroke internal combustion engine according to claim 8,
wherein each exhaust rocker arm comprises:
a cam follower located on one end of the exhaust rocker arm,
wherein the cam follower is adapted to follow a profile of an
exhaust cam lobe located on the camshaft; and
an exhaust hydraulic adjuster located on an opposite end of the
exhaust rocker arm, wherein the exhaust hydraulic adjuster is
adapted to contact and operate the exhaust valve in response to
movement of the exhaust rocker arm by the exhaust cam lobe.
10. The four stroke internal combustion engine according to claim
6, wherein the first actuator arm is spaced from the second
actuator arm.
11. The four stroke internal combustion engine according to claim
10, further comprising:
a spark plug assembly disposed in the cylinder head, wherein the
spark plug assembly is positioned between the first actuator arm
and the second actuator arm.
12. The four stroke internal combustion engine according to claim
11, wherein the longitudinal axis of the spark plug assembly
extends substantially parallel to the longitudinal axis of the
intake valves.
13. The four stroke internal combustion engine according to claim
11, wherein the longitudinal axis of the spark plug assembly and
the intake valve axis form an acute angle not greater than
20.degree..
14. The four stroke internal combustion engine according to claim
11, wherein the spark plug assembly comprises:
a tube assembly secured to the cylinder head;
a spark plug connector removably located within the tube assembly;
and
a spark plug secured to the spark plug connector.
15. The four stroke internal combustion engine according to claim
14, further comprising:
a pedestal within the cylinder head,
wherein the tube assembly is sealingly secured to the pedestal.
16. The four stroke internal combustion engine according to claim
14, wherein the tube assembly is plastic.
17. The four stroke internal combustion engine according to claim
14, wherein the spark plug connector further comprises:
a splash cover to prevent contaminants from entering the spark plug
assembly.
18. The four stroke internal combustion engine according to claim
2, wherein at least one of the cam shaft and the support axle is
offset with respect to the longitudinal axis.
19. The four stroke internal combustion engine according to claim
2, wherein the cam shaft is positioned closer to the exhaust valves
than the intake valves.
20. The four stroke internal combustion engine according to claim
2, wherein the cam shaft and the support axle are positioned closer
to the exhaust valves than the intake valves.
21. The four stroke internal combustion engine according to claim
2, further comprising:
a spark plug assembly connected to the cylinder head, wherein the
spark plug assembly comprises
a tube assembly secured to the cylinder head;
a spark plug connector removably located within the tube assembly;
and
a spark plug secured to the spark plug connector.
22. The four stroke internal combustion engine according to claim
21, further comprising:
a pedestal within the cylinder head, and
wherein the tube assembly is sealingly secured to the tube
assembly.
23. The four stroke internal combustion engine according to claim
21, wherein the spark plug connector further comprises:
a splash cover to prevent contaminants from entering the spark plug
assembly.
24. The four stroke internal combustion engine according to claim
21, wherein the spark plug connector further comprises:
a sealing assembly that forms a seal between the tube assembly and
the spark plug connector.
25. A personal watercraft for at least one passenger,
comprising:
a hull;
a seating assembly positioned on the hull adapted to accommodate at
least one passenger; and
an internal combustion engine located within the hull, wherein the
engine comprises
a crankcase secured to the hull having a crank shaft rotatably
mounted therein;
a cylinder head connected to the crankcase, wherein the crankcase
and the cylinder head form at least one cylinder;
at least one intake valve for the at least one cylinder, wherein
the at least one intake valve has an intake valve axis;
at least one exhaust valve for the at least one cylinder, wherein
the at least one exhaust valve has an exhaust valve axis;
a valve actuation assembly located in the cylinder head for
operating the at least one intake valve and the at least one
exhaust valve, wherein the valve actuation assembly is located
substantially between the intake valve axis and the exhaust valve
axis, the valve actuation assembly comprising
a cam shaft rotatably mounted within the cylinder head,
a support axle mounted within the cylinder head, offset from the
cam shaft;
at least one exhaust rocker arm pivotally mounted on the support
axle,
at least one intake rocker arm pivotally mounted on the support
axle,
wherein the cam shaft is operatively coupled to the crankshaft such
that rotational movement of the crankshaft is transferred to the
cam shaft,
wherein the at least one exhaust rocker arm is operatively coupled
to the cam shaft for operating the at least one exhaust valve,
and
wherein the at least one intake rocker arm is operatively coupled
to the cam shaft for operating the at least one intake valve;
and
a lubrication system for lubricating the engine,
wherein the lubrication system includes a supply of lubricant to
the cylinder head,
wherein the support axle has a central passageway extending
therethrough, and
wherein at least a portion of the supply of lubricant flows through
the central passageway in the support axle.
26. The personal watercraft according to claim 25, wherein the
crankshaft and the cam shaft extend generally parallel to a
longitudinal axis of the personal watercraft.
27. The personal watercraft according to claim 25, wherein each
cylinder has a longitudinal axis, wherein each of the at least one
intake valve and the at least one exhaust valve is disposed at an
angle with respect to the longitudinal axis.
28. The personal watercraft according to claim 27, wherein the
engine includes a pair of exhaust valves for each cylinder and the
valve actuation assembly includes an exhaust rocker arm for each
exhaust valve.
29. The personal watercraft according to claim 28, wherein each
exhaust rocker arm comprises:
a cam follower located on one end of the exhaust rocker arm,
wherein the cam follower is adapted to follow a profile of an
exhaust cam lobe located on the camshaft; and
an exhaust hydraulic adjuster located on an opposite end of the
exhaust rocker arm, wherein the exhaust hydraulic adjuster is
adapted to contact and operate the exhaust valve in response to
movement of the exhaust rocker arm by the exhaust cam lobe.
30. The personal watercraft according to claim 29, wherein the
exhaust hydraulic adjuster comprises:
an exhaust piston actuator slidably received within a cavity in the
end of the exhaust rocker arm; and
a fluid passageway extending through the exhaust rocker arm to the
support axle,
wherein the central passageway in the support axle is in fluidic
communication with the fluid passageway such that fluid within the
central passageway flows through the fluid passageway to the cavity
to bias the exhaust piston actuator into engagement with the
exhaust valve.
31. The personal watercraft according to claim 27, wherein the
engine includes a pair of intake valves for each cylinder and the
valve actuation assembly includes a forked intake rocker arm for
the pair of intake valves.
32. The personal watercraft according to claim 31, wherein the
forked intake rocker arm comprises:
a cam follower located on one end of the intake rocker arm, wherein
the cam follower is adapted to follow a profile of an intake cam
lobe located on the camshaft;
a first actuator arm for operating a first of the pair of intake
valves;
a second actuator arm for operating a second of the pair of intake
valves;
a pair of intake hydraulic adjusters located on an opposite end of
the forked intake rocker arm,
wherein the intake hydraulic adjuster is adapted to contact and
operate the pair of intake valves in response to movement of the
intake rocker arm by the intake cam lobe.
33. The personal watercraft according to claim 32, wherein each of
the intake hydraulic adjusters comprises:
an intake piston actuator slidably received within a cavity in an
end of the actuator arm, and a fluid passageway extending through
the actuator arm to the support axle, and
wherein the central passageway in the support axle is in fluidic
communication with the fluid passageway such that fluid within the
central passageway flows through the fluid passageway to the cavity
to bias the intake piston actuator into engagement with the intake
valve.
34. The personal watercraft according to claim 33, wherein the
exhaust rocker arms are rotatably mounted on the support axle on
opposite sides of the intake rocker arm.
35. The personal watercraft according to claim 34, wherein each
exhaust rocker arm comprises:
a cam follower located on one end of the exhaust rocker arm,
wherein the cam follower is adapted to follow a profile of an
exhaust cam lobe located on the camshaft; and
an exhaust hydraulic adjuster located on an opposite end of the
exhaust rocker arm, wherein the exhaust hydraulic adjuster is
adapted to contact and operate the exhaust valve in response to
movement of the exhaust rocker arm by the exhaust cam lobe.
36. The personal watercraft according to claim 35, wherein the
exhaust hydraulic adjuster comprises:
an exhaust valve actuator slidably received within a cavity in the
end of the exhaust rocker arm; and
a fluid passageway extending through the exhaust rocker arm to the
support axle,
wherein the central passageway in the support axle is in fluidic
communication with the fluid passageway such that fluid within the
central passageway flows through the fluid passageway to the cavity
to bias the exhaust valve actuator into engagement with the exhaust
valve.
37. The personal watercraft according to claim 33, wherein the
first actuator arm is spaced from the second actuator arm.
38. The personal watercraft according to claim 33, further
comprising:
a spark plug assembly disposed in the cylinder head, wherein the
spark plug assembly is positioned between the first actuator arm
and the second actuator arm.
39. The personal watercraft according to claim 38, wherein the
longitudinal axis of the spark plug assembly extends substantially
parallel to the longitudinal axis of the intake valves.
40. The personal watercraft according to claim 38, wherein the
longitudinal axis of the spark plug assembly and the intake valve
axis form an acute angle not greater than 20.degree..
41. The personal watercraft according to claim 38, wherein the
spark plug assembly comprises:
a tube assembly secured to the cylinder head;
a spark plug connector removably located within the tube assembly;
and
a spark plug secured to the spark plug connector.
42. The personal watercraft according to claim 41, further
comprising:
a pedestal within the cylinder head, wherein the tube assembly is
sealingly secured to the pedestal.
43. The personal watercraft according to claim 41, wherein one end
of the spark plug extends through a portion of the cylinder head
into the cylinder.
44. The personal watercraft according to claim 29, wherein at least
one of the cam shaft and the support axle is offset with respect to
the longitudinal axis.
45. The personal watercraft according to claim 44, wherein the cam
shaft is positioned closer to the exhaust valves than the intake
valves.
46. The personal watercraft according to claim 44, wherein the cam
shaft and the support axle are positioned closer to the exhaust
valves than the intake valves.
Description
FIELD OF THE INVENTION
The present invention relates generally to a new engine for use in,
for example, personal watercraft. In particular, the present
invention relates to a new four-stroke in-line engine that was
developed with a view to the future stricter environmental and
emission regulations. The engine has an improved valve train
arrangement for a lower engine profile and easy access to the spark
plug assembly.
BACKGROUND OF THE INVENTION
There is a very popular type of watercraft known as a "personal
watercraft" which is designed to be operated primarily by a single
rider. Although this type of watercraft is commonly employed for
single riders, frequently provisions are made for accommodating
additional passengers although the maximum number of passengers is
more limited than conventional types of watercraft.
This type of watercraft is also generally quite sporting in nature
and normally accommodates at least the rider on a type of seat in
which the rider sits in a straddle fashion. The passenger's area is
frequently open through the rear of the watercraft so as to
facilitate entry and exit of the rider and passengers to the body
of water in which the watercraft is operating, as this type of
watercraft is normally ridden with passengers that are wearing
swimming suits.
These personal watercraft are generally quite small so that they
can be conveniently transported from the owner's home to a body of
water for its use. Because of the small size, the layout of the
components is extremely critical, and this gives rise to several
design considerations that are peculiar to this type of watercraft.
However, due to its sporting nature it is also desirable if the
watercraft is powered by an engine and propulsion device that are
not only efficient but also generate sufficient power.
Traditionally, two-cycle engines have been used to power
watercraft, including personal watercraft. These engines have the
advantage that they are fairly powerful, relatively lightweight,
and compact.
One particular disadvantage to the two-cycle engine is its emission
content. Two-cycle engines generally exhaust larger quantities of
hydrocarbons and other pollutants than four-cycle engines due to
cylinder charging inefficiencies and the combustion of lubricating
oil among other things. When measures are taken to reduce emissions
of the two-cycle engine, other generally undesirable consequences
can result, such as an increase in the weight of the engine, a
reduction of its power output or the like. With concern for the
environment and increasingly strict emissions requirements being
instituted by various governing bodies. There is motivation to
provide a power plant that reduces exhaust emissions while
retaining other advantageous characteristics such as compactness,
low weight and high power output.
Four-cycle engines are commonly used as power plants in other
applications, such as automobiles. These engines have the advantage
that their emissions output are generally desirably lower as
compared to a two-cycle engine for a given power output. These
engines, however, are considerably larger than two-cycle engines
and therefor present difficulties when locating the engine in a
personal watercraft. It is desirable to provide an engine with a
reduced profile. This may be accomplished with proper configuration
of the valve train arrangement and cylinder head.
U.S. Pat. No. 4,267,811 to Springer, entitled "Cylinder Head For a
Mixture-Compressing Internal Combustion Engine," U.S. Pat. No.
4,553,515 to King et al., entitled "Cylinder Head For Spark
Ignition Internal Combustion Engine," U.S. Pat. No. 4,662,323 to
Moriya, entitled "Overhead Cam Type Valve Actuating Apparatus For
Internal Combustion Engine," U.S. Pat. No. 4,741,302 to Oda et al.,
entitled "Internal Combustion Engine," U.S. Pat. No. 4,773,361 to
Toki et al., entitled "Overhead Cam Type Four-Valve Actuating
Apparatus For Internal Combustion Engine," U.S. Pat. No. 4,796,574
to Fujii et al., entitled "SOHC Type Internal Combustion Engine,"
U.S. Pat. No. 5,009,204 to Ishii, entitled "Spark Plug Arrangement
In An Overhead Camshaft Engine," U.S. Pat. No. 5,095,859 to Iwata
et al., entitled "SOHC Type Internal Combustion Engine," U.S. Pat.
No. 5,513,606 to Shibata, entitled "Marine Propulsion Unit," U.S.
Pat. No. 5,829,402 to Takahashi et al., entitled "Induction System
For Engine," U.S. Pat. No. 5,839,930 to Nanami et al., entitled
"Engine Lubricating System For Watercraft," and U.S. Pat. No.
5,846,102 to Nitta et al., entitled "Four-Cycle Engine For A Small
Jet Boat" disclose various valve train arrangements for an internal
combustion engine. Each discloses positioning the intake and
exhaust valves at an angle within the cylinder head. Rocker arm
assemblies are used to actuate the valves. None of these
references, however, disclose using a single rocker arm having a
pair of operating arms to operate a pair of valves such that the
spark plug assembly is located between the operating arms of the
rocker arm. Furthermore, none of these references provides a spark
plug assembly that permits easy removal of the spark plug while
protecting the same from the elements.
OBJECTS OF THE INVENTION
It is an object of the present invention to provide a four stroke,
in-line engine having a compact construction.
It is another object of the present invention to provide a four
stroke, in-line engine having a modular construction to permit the
interchange of parts between various engine models.
It is another object of the present invention to provide a four
stroke, in-line engine having improved exhaust emission
characteristics.
It is another object of the present invention to provide a four
stroke engine having a narrow and low profile.
It is another object of the present invention to provide a four
stroke engine having a low profile valve actuation assembly for
controlling the operation of the intake and exhaust valves.
It is another object of the present invention to provide a cylinder
head having a low profile to reduce engine height.
It is another object of the present invention to offset the
placement of the intake valves and exhaust valves with respect to a
vertical axis within the cylinder head to reduce engine height.
It is another object of the present invention to provide an
improved spark plug mounting assembly for easy access within the
cylinder head.
It is another object of the present invention to provide a Y-shaped
intake rocker arm assembly providing compact construction.
It is yet another object of the present invention to provide a four
stroke engine having an improved oil collection system and oil
holding tank.
It is another object to provide a four stroke engine which combines
a closed loop cooling system and an open loop cooling system for
enhanced cooling of the engine in accordance with the present
invention.
It is another object to provide an open loop cooling system for
cooling an exhaust manifold in accordance with the present
invention, wherein the open loop cooling system enhances cooling of
the crankcase and cylinder head.
It is another object to provide an open loop cooling system for
cooling an exhaust manifold in accordance with the present
invention, wherein the open cooling system lowers the temperature
of the exhaust manifold such that the exhaust manifold functions as
a heat sink for the crankcase and cylinder head.
It is another object of the present invention to provide a closed
loop cooling system for selectively cooling the crankcase and
cylinder head of the four stroke engine.
It is another object of the present invention to provide a closed
loop cooling system having a selectively operable heat
exchanger.
It is another object of the present invention to provide a
supercharger for enhanced engine performance.
SUMMARY OF THE INVENTION
In accordance with the present invention, a four stroke internal
combustion engine is disclosed. In the preferred form, the engine
includes a crankcase having a crank shaft rotatably mounted
therein. A cylinder head is connected to the crankcase. The
crankcase and the cylinder head together form at least one
cylinder. Each cylinder has at least one intake valve and at least
one exhaust valve a crankshaft rotatably mounted within the
crankcase. A valve actuation assembly operates the intake valves
and the exhaust valves. The valve actuation assembly is located in
the cylinder head between the intake valve axis and the exhaust
valve axis.
In accordance with the present invention, the valve actuation
assembly includes a cam shaft that is rotatably mounted within the
cylinder head. It is preferable that the cam shaft is operatively
coupled to the crank shaft such that rotational movement of the
crankshaft is transferred to the cam shaft. A support axle is
mounted within the cylinder head and offset from the cam shaft. The
support axle has a central passageway. The valve actuation assembly
includes at least one exhaust rocker arm is pivotally mounted
within the cylinder head on the support axle. Each exhaust rocker
arm is operatively coupled to the cam shaft for operating the
exhaust valves. The valve actuation assembly also includes at least
one intake rocker arm is also pivotally mounted within the cylinder
head on the support axle. Each intake rocker arm is operatively
coupled to the cam shaft for operating the intake valves.
In accordance with the present invention, the engine further
includes a lubrication system for lubricating the engine. The
lubrication system includes a supply of lubricant to the cylinder
head. A portion of the supply of lubricant flows through the
central passageway in the support axle.
In order to reduce the overall profile of the engine and provide
sufficient space a spark plug assembly and the necessary crank gear
to cam gear ratio, the intake valves and exhaust valves are
disposed at an angle with respect to the longitudinal axis of the
cylinder. To accomplish this, the cam shaft and the support axle
are also offset with respect to the longitudinal axis. At least one
of the cam shaft and the support axle are positioned closer to the
exhaust valves than the intake valves. It is contemplated that the
longitudinal axis of the spark plug assembly extends substantially
parallel to the longitudinal axis of the intake valves. It is also
contemplated that the longitudinal axis of the spark plug assembly
and the intake valve axis may form an acute angle not greater than
20.degree..
In accordance with the present invention, each exhaust rocker arm
includes a cam follower located on one end of the exhaust rocker
arm. The cam follower is adapted to follow a profile of an exhaust
cam lobe located on the camshaft to operate the exhaust valves. An
exhaust hydraulic adjuster located on an opposite end of the
exhaust rocker arm. Each exhaust rocker adjuster includes a
slidable piston assembly that is adapted to contact and operate the
exhaust valve in response to movement of the exhaust rocker arm by
the exhaust cam lobe. A fluid passageway extends from the piston
assembly through the exhaust rocker arm to the support axle. Fluid
in the central passageway in the support axle flows through the
fluid passageway to bias the piston assembly into engagement with
the exhaust valve.
In accordance with the present invention, the valve actuation
assembly includes an intake rocker arm for operating a pair of
intake valves. Like the exhaust rocker arm, each intake rocker arm
includes a cam follower located on one end of the intake rocker
arm. Unlike the exhaust rocker arm, the intake rocker arm includes
a first actuator arm for operating a first intake valve, and a
second actuator arm for operating a second intake valve. Each
actuator arm includes a slidable piston assembly, as described
above. The cam follower and actuator arms have a generally
Y-shape.
In accordance with the present invention, the exhaust rocker arms
are rotatably mounted on the support axle on opposite sides of the
intake rocker arm. A spark plug assembly is positioned on the
cylinder head between the first actuator arm and the second
actuator arm.
The spark plug assembly includes a tube assembly secured to the
cylinder head. The tube assembly may be plastic. A spark plug
connector is removably located within the tube assembly. The spark
plug connector may include a splash cover to prevent contaminants
from entering the spark plug assembly. A spark plug is secured to
the spark plug connector.
The present invention is also directed to a personal watercraft for
at least one passenger having an internal combustion engine secured
to the hull below a seating assembly. The internal combustion
engine includes a valve actuation assembly, as described above and
described in greater detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described in conjunction with the following
drawings in which like reference numerals designate like elements
and wherein:
FIG. 1 is a downward rear schematic perspective view of a left side
of an overhead camshaft aspirated engine in accordance with the
present invention;
FIG. 2 is a downward rear schematic perspective view of a right
side of the engine of FIG. 1;
FIG. 3 is a downward front schematic perspective view of the left
side of the engine of FIG. 1;
FIG. 4 is a downward front schematic perspective view of the right
side of the engine of FIG. 1;
FIG. 5 is a rear end view of the engine of FIG. 1 illustrating one
possible positioning of the engine within a personal
watercraft;
FIG. 6 is a downward rear schematic perspective view of a variation
of the engine of FIG. 1 having a supercharger;
FIG. 7 is a rear end view of the engine of FIG. 6;
FIG. 8 is a partial cross-sectional end view of the crankcase and
cylinder head housing in accordance with the present invention;
FIG. 9 is a bottom view illustrating the upper crankcase of the
engine in accordance with the present invention;
FIG. 10 is a top view of the lower crankshaft illustrating the
positioning of the crankshaft and the balance shaft;
FIG. 11 is a right side partial schematic sectional view of the
engine of FIG. 6;
FIG. 12 is a partial schematic sectional view of the piston, valves
and valve actuator assembly in accordance with the present
invention;
FIG. 13 is a partial overhead schematic view of the rocker arm
assemblies of the valve operating assembly for operating the intake
and exhaust valves;
FIG. 14 is an end cross sectional view of one of the exhaust rocker
arm assemblies and a portion of the intake rocker arm assembly
taken along section line 14--14 of FIG. 13;
FIG. 15 is a cross sectional view of the operative end of the
rocker arm assemblies showing a collapsed position of the hydraulic
adjuster on the left side and an extended position of the hydraulic
adjuster on the right side;
FIG. 16 is a right side cross sectional view of the valve operating
assembly located within the cylinder head having the camshaft in
cross section;
FIG. 17 is another right side cross sectional view of the valve
operating assembly located within the cylinder head;
FIG. 18 is an end cross sectional view illustrating the spark plug
assembly within the cylinder head;
FIG. 19 is a cross sectional view illustrating the placement of the
cylinder head cover on the cylinder head;
FIG. 20 is a cross sectional view of the engine of FIG. 1 through
one cylinder of the engine;
FIG. 21 is a schematic perspective view of the exhaust manifold in
accordance with the present invention;
FIG. 22 is a longitudinal cross sectional view of a portion of the
exhaust manifold of FIG. 21;
FIG. 23 is a side cross sectional view of a portion of the exhaust
manifold of FIG. 21;
FIG. 24 is a schematic view of the exhaust manifold and open loop
cooling system in accordance with the present invention;
FIG. 25 is a schematic diagram of the cooling system for the engine
in accordance with the present invention;
FIG. 26 is a rear perspective view of a right side of the air
intake and fuel injection system for the engine in accordance with
the present invention;
FIG. 27 is a cross sectional view of the air intake and fuel
injection system of FIG. 26 taken along a longitudinal axis of the
system;
FIG. 28 is a side cross sectional view of the air intake and fuel
injection system of FIG. 26 through a swing pipe;
FIG. 29 is a variation of the air intake and fuel injection system
of FIG. 28 illustrating a cooling jacket within the swing pipe;
FIG. 30 is a front perspective view of a right side of the air
intake and fuel injection system for the engine having a
supercharger in accordance with the present invention;
FIG. 31 is a cross sectional view of the air intake and fuel
injection system of FIG. 30 taken along a longitudinal axis of the
system;
FIG. 32 is a rear view of the engine illustrating the power take
off lid and cooling system in accordance with the present invention
and the oil filter housing in partial cross section;
FIG. 33 is a side cross sectional view of a thermostat and pump
assembly of a portion of the cooling system and a lubrication pump
of the lubrication assembly in accordance with the present
invention;
FIG. 34 is a partial schematic/partial side cross sectional view of
an oil filter unit in accordance with the present invention;
FIG. 35 is a schematic diagram illustrating the oil channel system
for the lubrication system for the cylinder head housing;
FIG. 36 is a cross sectional side view of the power take off
assembly for the engine illustrating the generator assembly in
accordance with the present invention;
FIG. 37 is another cross sectional side view of the power take off
assembly for the engine illustrating the starter assembly in
accordance with the present invention;
FIG. 38 is a cross sectional side view of the power take off
assembly having a supercharger for the engine in accordance with
the present invention;
FIG. 39 is a partial schematic/partial sectional view of the cam
chain tensioner in accordance with the present invention;
FIG. 40 is a schematic view of the blow-by ventilation system and
suction pump in accordance with the present invention;
FIG. 41 is a schematic view of the blow-by ventilation system and
suction pump of FIG. 38 having the suction pump cover removed;
FIG. 42 is a schematic view of the engine management system for the
engine in accordance with the present invention;
FIG. 43 is a schematic perspective view of the exhaust manifold
according to an alternative embodiment;
FIG. 44 is a cross sectional view of a portion of the exhaust
manifold of FIG. 43;
FIG. 45 is a schematic diagram of the cooling system for the engine
in accordance with the present invention for use in connection with
the exhaust manifold of FIG. 43;
FIG. 46 is a cross sectional view of the cyclone of the blow-by
ventilation system;
FIG. 47 is a partial overhead cross sectional view of the engine of
FIG. 6 having a cut away of the balance shaft and the power take
off assembly;
FIG. 48 is an overhead view of the valve train;
FIG. 49 is a partial side cross sectional view of the balance shaft
and power take off assembly; and
FIG. 50 is a side view of the engine of FIG. 1 illustrating one
possible positioning of the engine within a personal
watercraft.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A four-stroke three cylinder in-line engine 1 in accordance with
the present invention is illustrated generally in FIGS. 1-4. The
engine 1 in accordance with the present invention will be described
in connection with a personal watercraft 5, shown in cross-section
in FIG. 5. A variation of the engine 1 is illustrated in FIGS. 6
and 7. The engine 2 shown in FIGS. 6 and 7 includes a supercharger.
The engines 1 and 2 are adapted to be installed below a raised
pedestal having a seating bench of the personal watercraft 5 inside
the hull 4, as shown in FIGS. 5 and 50. With this arrangement, the
oil filter cannot be placed on the lower side of the engine or of
its crankcase, respectively, if it is to be accessible for
maintenance purposes because the hull 4 would prevent access to the
oil filter. To address this, the oil filter is installed at the
power take off side of the engine, to be easily accessible from
above. The access through the seating area at present is the only
access to the engine.
While designed for use in personal watercraft, it is contemplated
that the engine 1 (or engine 2) can be used in all terrain
vehicles, snowmobiles, boats and other vehicles with minor
modifications. For example, the cooling system for the exhaust
manifold must be modified for non-marine applications. Further,
while the embodiments shown disclose an engine positioning with the
power take off to the rear of the engine, the orientation can be
altered to have the power take off to the front or to the side
depending on the specific vehicle or specific application.
Engine Configuration
The engine 1 includes a crankcase 10. A cylinder head housing 20 is
connected to the crankcase 10 to form a plurality of combustion
chambers. The crankcase 10 and cylinder head housing 20 are
inclined with respect to a vertical axis, as shown in FIGS. 5 and
8. This arrangement provides sufficient space for the air intake
and fuel injection system 40 while maintaining an overall reduced
engine profile. The engines illustrated and described herein
include three cylinders. The present invention, however, is not
limited to three cylinders; rather, it is contemplated that a
greater or fewer number of cylinders are considered to be well
within the scope of the present invention. For example, a single
cylinder version of the engine may be employed in a fishing boat.
Two or three cylinder versions of the engine may be employed in a
personal watercraft. A four cylinder version of the engine may be
employed in a jet boat. Four or more cylinders are considered to be
well within the scope of the present invention.
The engine 1 or 2 provides for the location of various engine
components including, but not limited to the starter assembly, the
generator, the oil pump, coolant pump and other devices at one end
of the engine in the power take off assembly 50, described below
and shown in FIGS. 33, 36, 37 and 38. This unique construction and
layout of components permits the use of similar parts and engine
components for one, two, three and four cylinder versions of the
engine. Furthermore, this arrangement permits the addition of
additional cylinders on the end of the engine opposite the power
take off assembly. The layout of the parts is the same. Minimal
redesign of these components is necessary when increasing or
reducing the number of cylinders.
The engine 1 contemplated herein includes an exhaust manifold 30
that is secured to one side of the cylinder head housing 20 and an
air intake and fuel injection system 40. The air intake and fuel
injection system 40 is secured to an opposite side of the cylinder
head housing 20 in the area above the cylinder head housing 20.
The present invention, however, is not limited to having a fuel
injection system; rather, it is contemplated that the engine can
instead be equipped with a carburetor.
A power take off assembly 50 is located on an end of the cylinder
block 10 within the hull 4. The power take off assembly 50 defines
the rear side of the engine when located within the personal
watercraft 5. The engine 1 or 2 further includes a lubrication
system 60 as shown in FIGS. 8 and 11. The engine 1 further includes
a blow-by ventilation system 70, as shown in FIG. 11, and an engine
cooling system 80, as shown in FIG. 25.
An engine 2 is shown in FIGS. 6 and 7, which is a variation of the
engine 1. The engine 2 has substantially the same configuration as
the engine 1. The engine 2 further includes a supercharger 90. The
use of a supercharger for an engine for use in a personal
watercraft is a new development, which is described in greater
detail below. The engine 1 can be converted with minor modification
to the engine 2 having a supercharger 90. In particular, as
described below, the supercharger 90 is attached to an opposite end
of the intake manifold 41 as compared to the normally aspirated
engine 1. The ignition and induction parameters of the engine may
be modified to enhance engine performance when the supercharger 90
is used. It is also contemplated that the compression ratio of the
engine may have to be altered to accommodate the supercharger 90.
In accordance with the present invention, it is contemplated that
the engines 1 and 2 will be produced on the same assembly line.
Because it is contemplated that the engine in accordance with the
present invention will be used in marine applications, the exterior
surfaces of the engines 1 or 2 will be provided with a suitable
coating to reduce corrosion and the direct exposure of the engine
to the elements. The individual components of the engines 1 and 2
will now be described in greater detail.
Crankcase
As illustrated in FIG. 8, the crankcase 10 contains a plurality of
passageways and compartments formed therein. Furthermore, the
crankcase 10 is formed with vertical partitions, as shown in FIGS.
9 and 10, which separate the individual crank chambers, described
below and external fins located on the crankcase 10. These vertical
partitions and external fins increase the strength of the crankcase
10. The spaced apart vertical fins provide additional strength for
an upper crankcase 13 of the crankcase 10 while minimizing the
weight. The vertical partitions increase engine strength and
separate the crank chambers 121 in the upper and lower crankcases
12 and 13. The vertical partitions also secure the upper and lower
crankcases together using suitable fasteners. The fasteners extend
through bores in the vertical partitions from a lower end of the
lower crankcase to the upper crankcase. The fasteners also serve to
secure the bearings, described below, within the vertical
partitions. The crankcase 10 is preferably formed from a cast
aluminum alloy (e.g. AlSi) for both strength and weight
considerations. The crankcase 10 is preferably die cast. The
present invention, however, is not limited to the use of aluminum
alloys; rather, other materials including but not limited to
steels, alloys and composites are considered to be well within the
scope of the present invention provided the materials have
sufficient strength for use in engine applications.
The crankcase 10 includes an upper crankcase 13 containing the
cylinder block and a lower crankcase 12. A balance shaft 115 and a
crankshaft 123 are located at the union between the lower crankcase
12 and the upper crankcase 13. An oil tank 11 formed in a bottom
portion of the lower crankcase 12, as shown in FIG. 8. The oil tank
11 has a generally u-shaped configuration that partially surrounds
a lower portion of a crankcase 12. The oil tank 11 is located on
both the bottom and side of the engine to house the necessary
volume of oil while maintaining the engine's reduced profile such
that oil is located on the bottom of the crankcase and the e side
of the crankcase 10. An interior of the upper crankcase 13 and the
lower crankcase 12 are connected to the oil tank 11 through outlet
openings 111, as shown in FIGS. 8 and 11. A channel 112 extends
from each opening 111 to an upper portion 113 formed in the lower
crankcase 13. The oil collected from the crank chamber 121 flows
through outlet openings 111 and channels 112, then enters the upper
channel portion 113 and returns to the oil tank 11. This oil then
flows under the influence of gravity downward into a lower portion
114 of the oil tank 11.
A balance shaft 115 extends through the crankcase 10. The balance
shaft 115 and the crankshaft 123 are located at the union of the
lower crankcase 12 and the upper crankcase 13. To prevent oil from
flowing from upper channel portion 113 and contacting the balance
shaft 115, an optional baffle assembly is located within the upper
portion 113. The balance shaft 115 is provided to counteract the
moment generated by rotation of the crankshaft 123, shown in FIG.
10. This arrangement produces mass balancing of the first order.
The balance shaft 115 and the crankshaft 123 extend in a parallel
relationship, as shown in FIG. 10. The balance shaft 115 is
rotatably mounted within a bore 1132 that extends through the
crankcase 10, as shown in FIGS. 9 and 10. Suitable bearing
assemblies are provided for smooth rotation of the balance shaft
115. The bearing assemblies are fixed using the fasteners described
above. Preferably, the balance shaft 115 should be mounted in an
anti-friction shell bearing but, alternatively, roller bearings can
also be used. The balance shaft 115 is operatively connected by
gear 1151 to the crankshaft 123 through gear 1231. This connection
is preferably located within the power take off assembly 50 on one
end of the crankcase 10.
The oil tank 11 forms a portion of a dry sump lubrication system.
The lubrication system and the operation of the same will be
described in greater detail below.
As FIGS. 9 and 10 illustrate, the crankcase 10 includes at least
one crank chamber 121 and in the preferred embodiment includes one
isolated crank chamber for each engine cylinder. In accordance with
the presently disclosed embodiments of engines 1 and 2, three crank
chambers 121 are provided. Each crank chamber 121 includes an
outlet opening 111 connected to the channel 112, described above. A
bore 122 extends through the crankcase 10 and each of the crank
chambers 121, as shown in FIGS. 9 and 10. A crankshaft 123 is
received therein, as shown in FIG. 10. The crankshaft 123 can be a
one-piece forging, cast or assembled depending upon the engine
application. For example, a cast crankshaft may be used in low
performance applications. The crankshaft 123 is rotatably mounted
within a bore 122. Suitable bearing assemblies are provided for
smooth rotation of the crankshaft 123.
As shown in FIG. 25, a cylinder 124 extends through the crankcase
10 above each of the crank chambers 121. In accordance with the
present invention, the engines 1 and 2 each include three cylinders
124, as shown in FIG. 11. A piston 1241 is slidably received within
the cylinder 124. The piston 1241, shown in FIG. 11, reciprocates
axially within the cylinder 124 as is known. The piston 1241 is
connected to the crankshaft 123 through a connecting rod 1242 and
piston pin 1243 to convert axial movement of the pistons 1241 to
rotational movement of the crankshaft 123 and vice-versa. A cooling
passageway 125 extends around the cylinders 124, as shown in FIG.
25. The cooling passageway 125 is connected to the engine cooling
system 80 further described below. As shown in FIG. 25, the cooling
passageway 125 extends substantially around the perimeter of the
cylinders. This passageway has a generally U-shaped
configuration.
At present, the cylinder liners are formed with grey cast iron. The
upper crankcase 13 is then cast around the liners. The upper
crankcase 13 may be formed from under-eutectic AlSi (e.g. cast-AlSi
9)(with 9% silicon). The interior of the cylinder liners may then
be honed. The use of grey cast iron increases the weight of the
crankcase 13. It is desirable to eliminate the use of the cylinder
liners. With this in mind, it is contemplated that the cylinder
liners may be eliminated. Instead, an interior surface of the upper
crankcase 13 can include a thermal coating to reduce friction. This
coating may be applied plasma spraying or other suitable process.
Alternatively, AlSi-alloys (alloys of aluminum and silicon) are
used to form the liners for the cylinders 124. The cylinder liners
may be formed from over-eutectic AlSi with primary silicon grains
therein (e.g. AlSi 19)(with 19% silicon) to minimize friction and
wear. The crankcase 10 may be formed from under-eutectic AlSi (e.g.
cast-AlSi 9)(with 9% silicon). The cylinder liners are assembled to
the cylinder block during the casting of the upper crankcase 13.
Beforehand, a binding layer consisting of eutectic AlSi 12 (with
12% silicon) is thermally sprayed (e.g. plasma sprayed) onto the
outer wall of the liner to provide a better bond and a better
heat-removal property (high heat transfer coefficient) between the
liner and the cylinder block 10. Alternatively, the cylinder liners
can also be inserted into the cylinder block of the upper crankcase
13 mechanically with a force fit. It is also contemplated that the
cylinder block 10 can be formed from over-eutectic AlSi (e.g. AlSi
19) without the need for separate cylinder liners. With this
arrangement, however, the cylinder is more difficult to machine,
more expensive and thus, is not presently preferred. In such a
liner-less embodiment, the cylinders can be optionally provided
with a surface coating for enhanced wear and friction properties.
It is contemplated that the pistons 1241 may be formed of aluminum
coated with iron.
Cylinder Head Housing
The cylinder head housing 20 is secured to the upper end of the
crankcase, as shown in FIG. 8. The cylinder head housing 20 is
bolted to the crankcase and provides a combustion chamber 201 above
each cylinder 124. A pair of exhaust valves 21 and a pair of intake
valves 22 are mounted in each combustion chamber 201. As shown in
FIG. 11, the pair of exhaust valves 21 are located on one side of
the cylinder head housing 20 and the pair of intake valves 22 are
located on an opposite side of the cylinder head housing 20. The
present invention, however, is not limited to a pair of exhaust
valves and a pair of intake valves; rather, a single exhaust valve
and a single intake valve may be employed. Furthermore, more than
two intake and exhaust valves may be provided. Furthermore, any
combination of intake and exhaust valves is contemplated provided
each cylinder includes more intake valves than exhaust valves.
As shown in FIG. 8, the intake valves 22 and the exhaust valves 21
are disposed at an angle with respect to the vertical axis of the
engine 1 or 2. This reduces the height of the cylinder head housing
20, which reduces the overall height of the engine 1 or 2.
The cylinder head housing 20 further includes at least one exhaust
passageway 23 for each combustion chamber 201 extending through the
cylinder head housing 20, as shown in FIGS. 8, 12 and 13. The
passageway 23 includes a pair of siamesed exhaust ports 231 that
connect the exhaust passageway 23 to the chamber 201, as shown in
FIGS. 12 and 13. Each of the pair of exhaust valves 21 is
positioned in one of the respective exhaust ports 231 to
selectively open and close the ports 231 at predetermined intervals
to permit the removal of exhaust gases from the chamber 201. An
opposite end of the exhaust passageway 23 has an opening 232, as
shown in FIG. 14, that is operatively connected to the exhaust
manifold 30. The exhaust manifold 30 is secured to the cylinder
head housing 20 using suitable fasteners on a downwardly facing
side of the cylinder head housing 20, as shown FIG. 5.
The cylinder head housing 20 further includes at least one intake
passageway 24 for each cylinder 124 extending through the cylinder
head housing 20, as shown in FIGS. 8, 12 and 13. The passageway 24
includes a pair of siamesed intake ports 241 that connect the
intake passageway 24 to the chamber 201. Each of the pair of intake
valves 22 is positioned in one of the intake ports 241 to
selectively open and close the openings 241 at predetermined
intervals to permit the influx of fuel and air into the chamber
201. An opposite end of the intake passageway 24 has an opening
242, as shown in FIG. 14, that is operatively connected to the air
intake and fuel injection system 40. The air intake and fuel
injection system 40 is secured to the cylinder head housing 20
opposite the exhaust manifold 30 using suitable fasteners on an
upwardly facing side of the cylinder head housing 20, as shown in
FIG. 5. While the intake and exhaust ports are shown as being
siamesed, they can alternatively remain separated until connected
to the respective intake and exhaust manifolds. The cylinder head
housing 20 includes a spark plug assembly 28 that is located in a
central inclined position, as described in greater detail
below.
Valve Operating Assembly
A valve operating assembly illustrated in FIGS. 8 and 12-17
operates the intake valves 22 and exhaust valves 21 in accordance
with predetermined engine operating parameters. The valve operating
assembly is located within the cylinder head housing 20 and is
driven by the crankshaft 123. As discussed in greater detail below
in connection with the power take off assembly 50, the crankshaft
123 extends from the crankcase 10 into a power take off housing 59.
A gear assembly 54 is secured to the crankshaft 123 within the
power take off housing 59 and includes a chain gear 542.
A cam shaft 29 is rotatably mounted within the cylinder head
housing 20. One end of the cam shaft 29 extends into a control
chain chamber 202 within the cylinder head housing 20. The control
chain chamber 202 extends into the cylinder block of the upper
crankcase and enters the power take off assembly 50. A cam gear 293
is operatively coupled to a chain gear 542 by a control chain 55,
which extends around both the gear 293 and gear 542. The control
chain 55 extends through the control chain chamber 202 into the
power take off assembly 50. The cam gear 293 and chain gear 542 are
sized to have a 2 to 1 relationship.
The camshaft 29 is rotatably mounted to the cylinder head housing
20 in a position between the intake and exhaust valves 21 and 22.
Suitable bearing assemblies are provided for the smooth operation
and rotation of the camshaft 29 within the cylinder head housing
20. As shown in FIG. 12, a plurality of cam lobes 291 and 292 are
provided along the camshaft 29 to operate the valves 21 and 22 in
each cylinder. A cam lobe 291 provides the necessary motion to
operate the intake valves 22 through the rocker arm assembly 25. A
pair of cams 292 provide the necessary motion to operate the
exhaust valves 21 through the rocker arm assemblies 26. A cam 291
and a pair of cams 292 are positioned over each cylinder, as shown
in FIGS. 16 and 17. The cams 291 and 292 are oriented on the
camshaft 29 to produce a predetermined timing for opening and
closing the valves 21 and 22. The orientation of the cams 291 and
292 vary for each cylinder such that all cylinders do not operate
at the same time, rather the cylinders operate in a predetermined
sequence. While the camshaft 29 is illustrated with a solid
construction, it is contemplated that the camshaft 29 may have a
hollow construction. Furthermore, the camshaft may be forged, cast
or assembled.
The valve operating assembly includes a Y-shaped intake rocker arm
assembly 25 that operates both of the pair of intake valves 22, as
shown in FIG. 13, in response to the cam lobe 291. The valve
operating assembly further includes a pair of exhaust rocker arm
assemblies 26 that operate the pair of exhaust valves 21, as shown
in FIG. 13, in response to cam lobes 292. The intake rocker arm
assembly 25 is a forked assembly rocker arm having a pair of valve
operating arms 251 and 252. One operating arm 251 operates one of
the intake valves 22 and the other operating arm 252 operates the
other intake valve 22. The fork like shape of the rocker arm
assembly 25 provides access to the spark plug assembly 27
positioned within the cylinder head housing 20. The spark plug
assembly 27 will be described in greater detail below. The fork
like shape of the rocker arm assembly 25 reduces the overall width
of the necessary assemblies to operate the valves for each
cylinder.
In an effort to reduce the weight of the rocker arm assemblies 25
and 26, the rocker arm assemblies 25 and 26 may be produced from an
aluminum alloy (AlSi) by forging or casting. The present invention,
however, is not limited to rocker arm assemblies formed from
aluminum; rather, it is contemplated that other materials including
but not limited to steel and alloys of the same may be cast or
forged to form the rocker arm assemblies 25 and 26.
The rocker arm assemblies 25 and 26 are rotatably mounted on a
rocker arm support axle 28 in a position between the intake and
exhaust valves 21 and 22. The stationary support axle 28 is mounted
to the cylinder head by a plurality of fastener assemblies 281, as
shown in FIGS. 16 and 17. The fastener assemblies 281 may include
screw type fasteners, pin fasteners or other similar fastener
assemblies for securing the support axle 28 within the cylinder
head housing 20 and preventing its rotation. The rocker arm support
axle 28 is mounted to the cylinder head housing 20. The axle 28 is
laterally offset and vertically spaced from the camshaft 29, as
shown in FIGS. 12, 14 and 18. This arrangement results in a compact
construction that reduces the overall height of the cylinder head
housing 20. It is contemplated that the axle 28 may be located on
the vertical axis of the cylinder or adjacent to the same.
The camshaft 29 is operatively connected to the crankshaft 123, as
described below. The cam gear associated with the crankshaft gear
are sized to have a 2 to 1 relationship. The angled intake and
exhaust valves 21 and 22 provide an enlarged area within the
cylinder head housing 20 between the valves in which to locate the
cam shaft, axle and the rocker arm assemblies 25 and 26. This also
provides sufficient space to maintain the 2 to 1 relationship
between the cam gear and the crankshaft gear without increasing the
height of the cylinder head housing 20.
The rocker arm assembly 25 will now be described in greater detail,
reference being made to FIGS. 12 and 14. As described above, the
rocker arm assembly 25 has a pair of operating arms 251 and 252. A
free end of each of the pair of operating arms 251 and 252 is
positioned over a respective intake valve 22 and includes an
hydraulic adjuster 253 for contacting the intake valve 22. The
hydraulic adjuster 253 abuts the upper surface of the valve stem of
the intake valve 22. The hydraulic adjuster 253 is located within a
cavity 2511 and 261 in the respective arm 251 and 252. A
passageways 2512 and 262 extend from the cavities 2511 and 262,
respectively, to the rocker arm support axle 28. The passageways
2512 and 262 are hydraulically linked to the rocker arm supportaxle
28. The rocker arm support axle 28 includes a central passageway
through which a supply of hydraulic fluid (preferably lubricant
from the lubricant system) or other suitable lubricant flows. The
fluid passes from the central passageway through radial openings
282 to the passageways 2512 and 262. The fluid flows through the
passageways 2512 and 262 to the cavities 2511 and 261 where it
biases the hydraulic adjuster 253 into contact with the intake
valve 22. The fluid insures that the hydraulic adjuster 253 is
always in contact with the intake valve 22 such that zero lash
exists between the valve and hydraulic adjuster 253. This insures
that the entire motion of the cam 291 is transferred to the intake
valves 22 to facilitate their opening and closing. Although fluid
is used to bias the hydraulic adjuster 253 into engagement with the
valves 22 in the embodiment illustrated, it is contemplated that a
screw adjuster assembly or other mechanical assembly can be
provided to perform the same operation.
An opposite end of the rocker arm assembly 25 includes a cam
follower 254. The follower 254 may include a roller assembly having
bearings that is rotatably mounted to the rocker arm assembly 25.
The follower 254 travels along the cam 291, which causes the rocker
arm assembly 25 to pivot about the rocker support axle 28. The
motion of the cam 291 is transferred to open and close the intake
valves 22. Fluid from the central passageway 281 may be directed
through another passageway, not shown, in the rocker arm assembly
25 to provide a supply of fluid to lubricate the follower assembly
254 to provide for smooth operation. The present invention,
however, is not limited to the roller followers described herein;
rather, it is contemplated that other followers including but not
limited to sliding blocks may be utilized to follow the cam
291.
The rocker arm assembly 25 has a compact angled construction, as
shown in FIG. 14 so as to allow for a narrow and low construction.
Similarly, the low arrangement of the camshaft 29 and associated
drive chain wheel, which also does not project beyond the cylinder
head housing 20, as seen in FIGS. 16 and 17 assists in constructing
an engine with a narrow and low profile.
As seen in FIGS. 8, 12 and 14, the camshaft 29 and the support axle
28 are offset relative to the longitudinal axis of the cylinder.
The camshaft 29 is offset to provide room for the spark plug
assembly 27, described below. Both the camshaft 29 and the support
axle 28 are located closer to the exhaust valves 21 than the intake
valves 22. The offset nature of the support axle 28 increases the
overall length of the intake rocker arm assembly 25. This increases
the lever arm of the intake rocker arm assembly 25 and maximizes
the force (within the size constraints of the cylinder head housing
20) applied to operate both intake valves 22 with one rocker arm
assembly. The intake and exhaust valves are disposed at an angle
with respect to the cylinder axis. In principle, however, also
other geometries (e.g. with a central arrangement of the camshaft
29) are conceivable. Alternatively, the rocker arm support axle 28
may be located closer towards the intake valves so as to make the
forked operating arms 251 and 252--which are heavy due to this
construction--shorter and thus less heavy. With this arrangement,
the location of the camshaft 29 should also be relocated to
maintain the lever arm of the intake rocker arm assembly 25.
The rocker arm assemblies 26 will now be described in greater
detail. Each exhaust rocker arm assembly 26 has the same
construction. A free end of the rocker assembly 26 is positioned
over a respective exhaust valve 21 and includes a hydraulic
adjuster 263 for contacting the exhaust valve 21. The hydraulic
adjuster abuts the upper surface of the valve stem of the exhaust
valve 21. Like the hydraulic adjuster 253, the hydraulic adjuster
263 is located within a cavity 261. A passageway 262 extends from
the cavity 261 to the rocker arm support axle 28. The passageway
262 is hydraulically linked to the rocker arm support axle 28
through radial openings 282. The fluid flows through the passageway
262 to the cavity 261 where it biases the operating assembly 263
into contact with the exhaust valve 21. The fluid ensures that the
hydraulic adjuster 263 is always in contact with the exhaust valve
21 such that zero lash exists between the valve and hydraulic
adjuster 263. This insures that all motion of the cam 292 is
transferred to the exhaust valve 21 to facilitate opening and
closing. Although fluid is used to bias the hydraulic adjuster 263
into engagement with the valve 21, it is contemplated that a
mechanical assembly (e.g. a screw adjuster) may be provided to
perform the same operation.
An opposite end of the exhaust rocker arm assembly 26 includes a
cam follower 264. The follower 264 has a similar construction to
the follower assembly 254, described above. The rocker arm assembly
26 also has a compact angled construction, as shown in FIG. 14 so
as to allow for a narrow and low construction.
The construction of the hydraulic adjusters 253 and 263 will now be
described in greater detail in connection with FIG. 15. The
hydraulic adjusters 253 and 263 have the same construction. The
hydraulic valve adjusters 253 and 263 are maintenance free and
require no adjustment. The hydraulic adjuster 263 is positioned
within the cavity 261. The hydraulic adjuster 263 includes an inner
stationary piston 2631 and an outer movable piston 2632, which is
located between the cavity 261 and the inner stationary piston
2631. The inner stationary piston 2631 includes a central cavity
2633 that is in communication with the cavity 261, as shown in FIG.
15.
An opposite end of the piston 2631 includes an aperture 2634 such
that the cavity 2633 is in fluidic communication with a cavity 2635
in the piston 2632. A ball and seat check valve 2636 selectively
closes the aperture 2634. A valve contacting cap 2637 is pivotably
mounted on an end of the piston 2632. The cap 2637 contacts the
valve stem of the exhaust valve 22 when the piston 2632 is in an
extended position, as shown in the right side of FIG. 15.
In operation, hydraulic fluid flows through channel 262 into the
cavity 261. After the cavities 261 and 2633 have filled with fluid,
the valve 2636 opens to permit the flow of fluid into cavity 2635
through aperture 2634. As the cavity 2635 fills with hydraulic
fluid, the piston 2632 extends to the position shown in the right
side of FIG. 15. The spring assembly 2638 is located in the cavity
2635. The downward travel of the piston 2632 is limited by contact
with the valve stem and a seal 2639 that is secured to one end of
the piston 2632 and is slidably received around the piston 2631.
When in the normal downward steady state position, the contacting
cap 2637 contacts the valve stem such that motion of the rocker arm
assembly is transferred to the valve to open the valve at
predetermined locations of the camshaft 29. After engine shut off,
a sufficient amount of fluid is maintained in the cavity 2635 to
maintain the outer movable piston 2632 in engagement with the
corresponding valve stem.
FIGS. 16 and 17 illustrate an axial section through the camshaft 29
and the rocker arm support axle 28. The camshaft 29 is mounted in a
bearing bracket 293 with two collars 294 and 295. Lubricant is
supplied to the clearance region between these two collars 294 and
295. By means of this double plain bearing in the respective
bearing bracket 293, the bearing becomes very rigid and the dynamic
changing loads occurring during operation can be accommodated
efficiently. Mounting of the camshaft 29 is effected by inserting
it in from one end of the cylinder head housing 20 near the power
take off end of the engine. The camshaft 29 is secured by a plate
positioned within the cylinder head housing 20 against axial
shifting. The plate extends through a vertical slot located within
the cylinder head housing 20. The plate may be further used to
orient the axle 28 within the cylinder head housing 20. It is also
contemplated that a pin may be used to secure the camshaft against
axial shifting. The pin may be located in a slot or groove
extending around the perimeter of the camshaft.
Although the operation of the intake valves 22 and exhaust valves
21 has been described in connection with rocker arm assemblies 25
and 26, other assemblies are contemplated for operating the valves.
For example, the valves may be electromagnetically operated.
Alternatively, the valves may be hydraulically operated using a
slave piston/master piston arrangement. Furthermore, the Y-shaped
rocker may be used to actuate the exhaust valves. Individual rocker
arms may be used to operate intake valves. With this arrangement,
the location of the spark plug assembly 27 must be relocated. It is
also contemplated that gas springs may be used to bias the valves
into a closed position when high rotation speeds are desired for
high rpm output. It is also contemplated that a variable valve
train may be substituted to vary the timing of the valve
operation.
Spark Plug Assembly
The spark plug assembly 27 will now be described in greater detail
in connection with FIG. 18. A spark plug 271 is connected by
threaded engagement to the cylinder head housing 20, as shown in
FIG. 18 such that an electrode portion of the spark plug 271
extends into the cylinder. The spark plug assembly 27 is located
between the intake valves 22 and the exhaust valves 21 closer to
the intake valves 21 because the intake side of the engine is
cooler than the exhaust side of the engine. It is desirable to
isolate the spark plug 271 from the remainder of the cylinder head
housing 20, which contains oil therein. A tube assembly 272
surrounds the spark plug 271. The tube assembly 272 is preferably
formed from a die cast plastic. It, however, is contemplated that
other light weight materials may be used to form the tube assembly
272 so long as the tube assembly 272 isolates the spark plug 271
from the oil-carrying portions of the cylinder head housing 20. It
is preferable that the spark plug assembly 27 be inclined at an
angle with respect to the central axis of the cylinder. The angle
between the spark plug assembly and the intake valves is small
(e.g. 3.degree. is preferable). The angle, however, may be
zero.
Each tube assembly 272 is sealingly inserted into a pedestal 273 on
the cylinder head housing 20, which forms a socket for the spark
plug 271. A slight compression fit between the tube 272 and a bore
in the pedestal 273 can provide a sealing engagement between the
two components although this sealing engagement can also be
augmented by providing an o-ring between the two compartments. On
an outer end, a seal 274 is vulcanized onto the tube assembly 272
which effects the sealing between the tube assembly 272 and a
cylinder head cover 275. Alternatively, the seal 274 can be
provided as a separate component between the tube 272 and cover
275. Use of the tube 272 provides for a lighter weight head
assembly and also simplifies the casting of the cylinder head since
the isolating tube is not cast as part of the cylinder head. The
tube assembly 272 accommodates a plastic body spark plug connector
276 in which the ignition coil or the spark transformer are cast.
In this way, the path of the high voltage to the spark plug 271 can
be kept extremely short. From the outside, only a low voltage is
supplied to the plastic body spark plug connector 276 and the
ignition coil contained therein. The plastic body spark plug
connector 276 and the spark plug 271 can easily be removed through
the tube assembly 272. The plastic body spark plug connector 276
abuts the inner side of the tube assembly 272. A venting assembly
is provided to enable venting from the spark plug region towards
the environment. A splash water screen 2763 is attached to the
plastic body 276.
A cylinder head cover 275 is attached to the cylinder head housing
20 using a plurality of fastener elements 2571, as shown in FIG.
19. The cylinder head cover 275 is preferably formed from aluminum
or some synthetic material. The connection between the cylinder
head housing 20 and the cylinder head cover 275 is acoustically
decoupled. An elastomeric gasket 2753 is positioned between the
cylinder head housing 20 and the cylinder head cover 275 to provide
a seal between the two components. The gasket 2753 has a protruding
portion 2754 that is configured to sealingly engage a slot 2755 in
the cylinder head cover 275. This engagement maintains the gasket
in a desired position between the cylinder head housing 20 and the
cylinder head cover 275 and helps prevent the gasket 2753 from
dislocating and causing leaks. In addition, the elastomeric gasket
also reduces and prevents a direct sound propagation from the
cylinder head housing 20 to the cylinder head cover 275 thereby
reducing overall noise emanating from the engine. A further
elastomeric gasket 2752 is provided between the fastener element
2751 and cylinder head cover 275 to seal the connection
therebetween and also block direct sound propagation from the
cylinder head housing 20 to the cylinder head cover 275 through the
fastener 2751. With this arrangement, the cylinder head cover 225
is isolated from the cylinder head housing 20.
Exhaust Manifold
A preferred embodiment of the exhaust manifold 30 will now be
described in connection with FIGS. 21-24. The exhaust manifold 30
includes a first manifold 31 and a second manifold 32, as shown in
FIG. 24. The first manifold 31 is connected to one side of the
cylinder head housing 20. It is preferably located on the smaller
downward facing side of the cylinder head housing 20 because it
does not require as much space as the induction system 40,
described below. The first manifold 31 includes at least one
exhaust passageway 311 that is operatively coupled to each exhaust
passageway 23 in the cylinder head housing 20. Each exhaust
passageway 311 connects to a main exhaust passageway 312, which
extends in a direction towards the power take off assembly 50. With
this arrangement, exhaust gases exit the cylinder head housing 20
through each exhaust passageway 23 when the respective exhaust
valves 21 are opened. The exhaust gases then travel through the
exhaust passageway 311 to the main exhaust passageway 312.
The first manifold 31 is connected at the end nearest the power
take off assembly 50 to the second manifold 32. The second manifold
32 includes a main exhaust passageway 321. The exhaust gases travel
through the main exhaust passageway 321 into the muffler system
33.
Due to US Government regulation, it is necessary to cool the
exhaust components to limit the temperature of these components
below a threshold value. It is desirable to cool the exhaust gases
as the gases pass through the exhaust manifold 30 and an associated
muffler system 33. The muffler system 33 preferably includes a
first muffler 331 directly connected to the exhaust manifold 30 and
a second muffler 332 connected to the first muffler 331.
The first and second manifolds 31 and 32 are equipped with an open
loop cooling system for cooling the manifolds 31 and 32 and the
exhaust gases contained therein. Each manifold 31 and 32 has a
double jacket construction that permits cooling water to flow
around the interior of the manifolds 31 and 32 without mixing with
the exhaust gases. The first manifold 31 is preferably cast. The
second manifold 32 is preferably formed from stainless steel.
The first manifold 31 has an inner manifold 313 and an outer
manifold 314, as shown in FIGS. 22 and 23. The spacing between the
inner and outer manifolds 312 and 314 forms a cooling passageway
315. The inner and outer manifolds 313 and 314 are interconnected
at various points along the manifold. The cooling passageway 315
has a generally u-shaped configuration when viewed from a vertical
cross section such that it surrounds the main passageway 311 on the
top, bottom and at least one side. The cooling water enters the
passageway 315 through at least one inlet 316. The cooling water
then travels through the cooling passageway 315 and exits through
at least one outlet 317.
The second manifold 32, as shown in FIG. 24, also has an inner
manifold 322 and an outer manifold 323. The spacing between the
inner and outer manifolds 322 and 323 forms a cooling passageway
324, therebetween. The cooling passageway 324 substantially
surrounds the main exhaust passageway 321. The cooling water enters
the cooling passageway 324 through at least one inlet 325 located
near the connection between the first manifold 31 and the second
manifold 32. The cooling water exits the cooling passageway through
at least one outlet 326 located near the point where the second
manifold 32 enters the first muffler 331.
The cooling system for the exhaust manifold 30 and muffler system
33 is an open loop cooling system. Cooling water is supplied to the
first and second manifolds 31 and 32 by a jet pump of the
propulsion unit of the personal watercraft 5, which draws cooling
water from the body of water in which the personal watercraft 5 is
operating. An open loop cooling system can be used for the exhaust
manifold 30 because the geometry of the cooling jacket for the
exhaust manifold 30 is relatively simple with larger passageways.
There is less concern for the clogging of these passageways. On the
contrary, the geometry of the cooling system for the cylinder head
housing 20 and crankcase 10 is more complex with smaller
passageways. There is a greater concern about clogging that may
occur when using a coolant drawn from outside the watercraft 5. As
such, a closed loop cooling system is preferred for the cylinder
head housing 20 and crankcase 10.
The cooling passageways 315 and 324 sufficiently cool the manifolds
31 and 32. The temperature of the exhaust gases, however, remains
too high. It must be further cooled before venting to the
atmosphere or released into the water. It is desirable to cool the
exhaust gases as the exhaust gases enter the first muffler 331. At
least one injection nozzle 34 is located adjacent the end of the
main exhaust passageway 323, such that a stream of cooling water is
injected into the exhaust stream as the exhaust stream enters the
first muffler 331. Although it is preferable that the at least one
injection nozzle 34 be located within the muffler 331, it is
contemplated that the injection nozzles 34 may be located within
the main exhaust passageway 323.
It is possible for the personal watercraft 5 to overturn or
rollover during operation. It is desirable to prevent the cooling
water used to cool the exhaust gases from traveling within the main
exhaust passageways 314 and 323 to the cylinder head housing 20.
The design of the second manifold 32 and the connection between the
second manifold 32 and the first muffler 331 prevent the return of
the cooling water to the cylinder head housing 20.
The second manifold 32 terminates within the first muffler 331 at a
central location. The outlet opening for the main exhaust
passageway 323 is spaced from the top, bottom and side walls of the
first muffler 331. With this arrangement, cooling water that has
accumulated within the first muffler 331 should not enter the main
exhaust passageway 323 because the cooling water should travel
along the sides of the first muffler 331 (spaced from the outlet)
when rollover occurs.
In the event that some cooling water enters the main exhaust
passageway 323, the configuration of the second manifold 32
prevents passage of cooling water to the cylinder head housing 20.
The second manifold 32 contains a unshaped bend or gooseneck
portion that traps the cooling water. With this arrangement in a
rollover condition, the cooling water must first travel downward
from the first muffler 331 through the bend or gooseneck portion
and then upward before entering the first manifold 31. The change
in direction of the main exhaust passageway 323 in the gooseneck
portion essentially prevents any cooling water from entering the
first manifold 31 or the cylinder head 32.
The present invention is not limited to the above-described
gooseneck portion for preventing water from entering the first
manifold 31 at the cylinder head 20; rather, other geometries that
produce a similar effect are considered to be well within the scope
of the present invention.
An alternative embodiment of the exhaust manifold will now be
described in connection with FIGS. 43 and 44. The exhaust manifold
300 is connected to one side of the cylinder head housing 20. Like
the manifold 30 described above, the manifold 300 is preferably
located on the smaller downward facing side of the cylinder head
housing 20. The exhaust manifold 300 includes at least one exhaust
passageway 310 that is operatively coupled to each exhaust
passageway 23 in the cylinder head housing 20. Each exhaust
passageway 310 connects to a main exhaust passageway 320. The
exhaust gases exit the cylinder head housing 20 through each
exhaust passageway 23 when the respective exhaust valves 21 are
opened. The exhaust gases then travel through the exhaust
passageway 310 to the main exhaust passageway 320. The main exhaust
passageway 320 first directs the exhaust gases toward the front of
the personal watercraft, then in an opposite direction through knee
bend 330 toward the rear of the personal watercraft. The exhaust
gases may then exit the exhaust manifold 300 to a muffler system
and/or water trap. The muffler system may include a pair of
mufflers.
In this alternative arrangement, the exhaust manifold 300 also has
a double jacket construction that permits cooling water to flow
around the exhaust gases without mixing the cooling water and the
exhaust gases. The double jacket construction includes an inner
manifold 340 and an outer manifold 350, which create a cooling
chamber 370 therebetween. Webs 360 separate the cooling chamber 370
into a first portion 3701 and a second portion 3702, as shown in
FIG. 22. The cooling water passes through the cooling chambers 3701
and 3702, as shown in FIG. 44.
Like the manifold 30 the exhaust manifold cooling system is an open
loop cooling system. As such, a jet pump of the propulsion unit
draws cooling water from the body of water in which the personal
watercraft 5 is operating, shown in FIG. 44. The cooling water is
supplied to the exhaust manifold 300 through a primary inlet port
3510 located in the bend 330 of the exhaust manifold 300, as shown
in FIG. 43. The cooling water then flows through the first chamber
portion 3701 until it connects with the second chamber 3702 at the
rear portion of the exhaust manifold 300. The cooling water then
flows back through the second chamber 3702 until it is discharged
through the outlet port 3520 back into the body of water. Thus, the
separation of the chamber 370 into two portions 3701 and 3702 that
are interconnected only at an end of the exhaust manifold distant
from the cooling intake and outlet ports provides for a U-shaped
cooling circuit in the manifold, enhancing the cooling efficiency
of the manifold.
These cooling arrangements maintain the exhaust manifolds 30 and
300 at a lower temperature than the cylinder head housing 20 and
the cylinder block 10. As a result, the exhaust manifolds 30 and
300 function as a heat sink, withdrawing heat from the cylinder
head housing 20 and the cylinder block 10. This reduces the cooling
requirements placed on the closed loop cooling system 80, described
below. The coolant in the exhaust manifold (e.g. the water drawn
from the body of water) has a lower temperature than the coolant
for the closed loop cooling system, described below.
At least one temperature sensor 39 is located in the muffler to
measure the temperature of the exhaust gases. The exhaust manifold
300 is equipped with an injection cooling system, which supplies
additional cooling water to the exhaust manifold. A first injection
nozzle 381 sprays cooling water directly into the exhaust
passageway 320 in a direction away from the cylinder head housing
20. A second injection nozzle 383 sprays cooling water directly
into the exhaust passageway 320 also in a direction away from the
cylinder head housing 20. The location of the nozzles in the knee
of the exhaust manifold prevents the backward travel of the cooling
water into the cylinder head. The combined open loop cooling system
with the injection cooling system functions to cool both the
exhaust manifold and the exhaust gases within the manifold.
Air Intake and Fuel Injection System
The air intake and fuel injection system or induction system 40
will now be described in connection with FIGS. 26-31. The system 40
is connected to the cylinder head housing 20 opposite the exhaust
manifold 30. The air intake into the engine 1 or 2 is effected from
within the hull of the personal watercraft 5 via an air box, not
shown, but disclosed in US Provisional Patent Application No.
60/224,355, filed on Aug. 11, 2000, entitled "WATERCRAFT HAING
AIR/WATER SEPARATING DEVICE" and US Provisional Patent Application
No. 60/229,340, filed on Sep. 1, 2000, entitled "PERSONAL
WATERCRAFT HAING IMPROVED FUEL, LUBRICATION AND AIR INTAKE SYSTEMS"
the specifications of which are incorporated specifically herein by
reference. The air box comprises an air inlet in the form of a
snorkel, a water separator unit and a muffler unit. The air box is
located apart from the engine and connected to the engine via a
tube or hose to prevent water from entering the air intake
system.
The air flows through the tube connecting the air box with the
engine, and then passes to an air intake manifold or plenum 41,
illustrated in FIGS. 26-31. The air manifold 41 is preferably
formed from a plastic material. The present invention, however, is
not limited to the use of a plastic material; rather, metals, high
strength alloys and other suitable synthetic materials may be
used.
The air manifold 41 has a symmetrical geometry. With this
arrangement, air flow into the air manifold 41 can be provided at
either end of the air manifold 41, thereby enabling use of the same
air manifold 41 in either a normally aspirated engine 1 or a
supercharged engine 2, which engines have different flow paths for
air into the air intake manifold. In the normally aspirated engine,
the air from a throttle (if the engine has fuel injection) or a
carburetor (if the engine does not have fuel injection) flows into
one end of the air manifold 41, as shown for example in FIG. 4.
Preferably, this end faces the airbox to shorten the distance and
the pressure loss between the intake manifold and the airbox.
Irrespective of which end of the air manifold is used to intake
air, in a fuel injection version of the engine, the air manifold 41
includes a throttle body 411 containing a throttle at the plenum
inlet to regulate the flow of air into the manifold 41. The degree
of opening of the throttle of the throttle body 411 is controlled
by the engine management system 200. The throttle body 411 further
includes a by-pass idle valve 4111. The by-pass idle valve 4111 is
preferably controlled by a stepper motor that controls the cross
sectional opening of the by-pass idle valve 4111 and the amount of
air flowing through it. Alternatively, it is contemplated that the
idle valve 4111 may include an electromagnetically operated valve.
The operation of the by-pass idle valve 4111 is controlled by the
engine management system 200. The engine management system operates
the stepper motor based on the engine speed to adjust it to a given
threshold value. In normal operation, the idle valve 4111 is open
when the throttle of the throttle body 411 is closed. This permits
the flow of a predetermined amount of air into the manifold 41
during an engine idling less than the normal air intake into the
air manifold 41. The idle valve 4111 is not fully closed when the
throttle of the throttle body 411 is open. In a normal full load
steady state operating condition, the idle valve 4111 is partly but
not entirely open. This provides a reserve of intake air used for
transient engine operating conditions (e.g., a rapid deceleration
phase). The stepper motor is operated such that the maximum amount
of air can be drawn into the air manifold 41 so that the air/fuel
mixture is not too high. The location of the throttle body 411 is
different for the normally aspirated engine 1 and the supercharged
engine 2. It is contemplated that the throttle body 411 may be
replaced by a carbureter in a non-fuel injected version of the
engine.
The air manifold 41 further includes at least one swing pipe 412
for each cylinder. Each swing pipe 412 is operatively connected to
the respective intake passageway 24 to supply air to the combustion
chambers through intake openings 241. The flow pattern of the air
within the air manifold 41 is indicated by the arrows in FIGS.
27-29 and 31. As shown, the air enters the air manifold 41 via the
throttle body 411. The air passes radially through a cylindrical
flame arrester 42 and then flows through each swing pipe 412 to the
respective intake passageway 24. The end cap 413 made be integrally
formed with the air manifold.
The flame arrester 42 in the air manifold 41 prevents backfire of
flames from entering the engine compartment interior within the
hull of the personal watercraft. The flame arrester 42 includes a
perforated inner pipe 421 and a pleated porous outer shell 422. In
accordance with the present invention, the location of the flame
arrester 42 is advantageous. The flame arrester 42 is located
within the central passageway in the air manifold 41. As such, the
flame arrester 42 is located between the swing pipe 412 and the air
inlet. In the event of a backfire, this location is advantageous
because all flames are caught by the flame arrester 42 before
passage to the air inlet (i.e., the throttle or the supercharger).
Thus, backfire flame cannot reach outside of the engine, especially
important when the engine is installed on a watercraft or aircraft
where an engine compartment fire can be more disastrous than in an
automobile. Although a cylindrical flame arrester 42 is
illustrated, it is also contemplated that the flame arrester may be
in the form of a flat plate or an arcuate member.
The air manifold 41 is constructed to withstand the build up of
back pressure in the event of a backfire. The manifold 41 is
configured such that the back pressure is dissipated within the
swing pipe 412. To prevent failure or cracking of the manifold in
the event of a significant build up of back pressure, a pressure
relief valve may be provided. The pressure relief valve may be made
integral with an end cap 413, which is secured to an end of the air
manifold 41, as shown in FIG. 27.
In the supercharger version of the engine 2, the supercharger 90
and the throttle body 411 are interconnected between the air box
and the air manifold 41. The throttle body 411 is located between
the air manifold 41 and the supercharger 90. The supercharger
assembly 90, however, is connected to an opposite end of the air
manifold 41, as shown in FIGS. 30 and 31. The location of the
throttle body 411 is also relocated to this end. As such, the air
manifold 41 is designed such that the throttle body 411 and the
pressure relief valve, if provided, can be located on either end of
the manifold 41 to provide increased flexibility such that the same
manifold geometry can be used for either the supercharger version
or the normally aspirated version of the engine.
The intake manifold 41 also includes at least one drainage port.
The drainage plug is removably located within the drainage port. In
the event that water enters the interior of the intake manifold 41,
the plugs can be removed to drain the water. Alternatively, a hose
can be connected to the drainage port having a valve at an opposite
end for more controlled drainage. Furthermore, it is contemplated
that an automatically operated drainage valve may be provided to
drain the air manifold upon engine shutdown.
It is contemplated that the air manifold 41 may include a cooling
jacket 49 along an exterior wall of the air manifold 41, as shown
in FIG. 29. The cooling jacket 49 cools the air within the air
manifold 41 and, more particularly, the swing pipe 412 before
entering the combustion chambers. The cooling of the intake air is
especially useful for a supercharge version of the engine because
the operation of the supercharger (by compressing) the air
increases the temperature of the air. The cooling jacket may be
linked to the open loop cooling system.
The air intake and fuel injection system 40 further includes a fuel
injection assembly 43. The fuel injection assembly 43 includes a
common fuel rail 431. The fuel rail 431 extends along an upper
portion of the intake manifold 41, as shown in FIGS. 26, 27, 30 and
31. It is preferred that the pressure of the fuel into the fuel
rail 431 be regulated by the fuel supply assembly 203 located in
the fuel tank 204. In an arrangement where the fuel supply is not
controlled in the fuel tank, an optional pressure control valve 432
is located at one end of the fuel rail 431. The pressure control
valve 432 is provided to control fuel pressure within the fuel
injection assembly 43. In this arrangement, a separate fuel return
line is required.
At least one fuel injection nozzle 434 extends from the fuel rail
431 to the each swing pipe 412 adjacent the connection to each
intake passageway 24. A fuel injection nozzle 434 is provided for
each engine cylinder. The swing pipe 412 extends along the sides of
the fuel injection nozzle 434. This increases air flow around the
injection nozzle 434 such that no pockets of reduced air flow are
produced adjacent the nozzle 434 because reduced air flow may
produce residue on the wall of the swing pipe adjacent the nozzle,
which could reduce performance and flow of fuel into the cylinder
chamber. Additionally, to prevent the formation of pockets, the
nozzles 434 may extend into the swing pipe 412. Fuel from the
injection nozzle 434 is mixed with the air within the swing pipe
412 as the air enters the intake passageway 24. The fuel injection
nozzles 434 are electromagnetically controlled by the engine
management system 200 so that the nozzles 434 are independently and
sequentially operated.
Power Take Off Assembly
The power take off assembly So of the engine 1 or 2 will now be
described in connection with FIGS. 32-34 and 36. The crankshaft
123, described above, extends from one end of the crankcase 10, as
shown in FIG. 33. The rotation motion of the crankshaft 123 is
transferred to a drive shaft 51. A threaded connecting assembly 52
is secured to the end of the crankshaft 123. The threaded
connecting assembly 52 includes a plurality of teeth 521 that
extend around an inner periphery of one end of the connecting
assembly 52. The teeth 521 are adapted to mate with complementary
teeth 511 on the drive shaft 51. As shown in FIGS. 36 and 37, the
teeth 511 have a generally arcuate shape. Although a generally
linear tooth arrangement is considered to be well within the scope
of the present invention, the arcuate tooth is preferred. The
arcuate arrangement allows for slight angular deviations between
the crankshaft 123 and the drive shaft 51. This is especially
important when the crankshaft 123 and the drive shaft 1 are not in
exact alignment or when the personal watercraft is operated in
extreme conditions, such as, for example, when jumping waves. The
use of the threaded connecting assembly 52 is also advantageous. In
the event of wear resulting from non-exact alignment, only the
connecting assembly 52 need be replaced.
The arcuate teeth 511 of the connecting assembly 52 are lubricated
with engine oil. The oil is supplied from a first crankshaft main
bearing 1232 via hollow bores 1233 in the crankshaft 123. The oil
then flows to the arcuate teeth 511. This arrangement reduces
engine maintenance because the operator no longer needs to grease
the connection between the crankshaft and the drive shaft. The
lubrication is performed by the lubrication system of the engine.
The power take off housing 59 seals the components contained
therein with the power take off assembly 50. Thus, protecting these
components from exposure to marine conditions.
The connecting assembly 52 includes a sealing extension 522,
wherein the extension 522 extends along a portion of the drive
shaft 51. An o-ring seal 523 or other suitable sealing member is
positioned between the sealing extension 522 of the connecting
assembly 52 and the drive shaft 51. There is no relative rotational
movement between the drive shaft 51 and the connecting assembly 52.
As such, there are no rotational stresses on the o-ring seal 523.
The sealing extension 522 and the o-ring 523 prevents lubricant
from escaping from the engine. A labyrinth sealing arrangement may
be provided between the sealing extension 522 and the power take
off housing 59 to prevent the passage of lubricant from the power
take off assembly 50 around the drive shaft 51. Alternatively, a
screw or worm conveyor may be provided, which conveys lubricant
back to the power take off assembly. At least one bore may be
provided to form a shortcut such that the oil is drawn into the
screw conveyor.
Additionally, the sealing of the drive shaft 51 with respect to the
outside is effected by a sealing assembly 53. The sealing assembly
53 includes several sealing elements that can be used alone or in
combination. The sealing assembly 53 includes flexible bellows 531,
a shaft seal ring 532, and sealing rings 533. The flexible bellows
531 connects the power take off housing 59 with an external bearing
carrier race 5311, which in turn is rotatably mounted on the drive
shaft 51 via two self lubricating antifriction bearings (rolling
bearings) 5312 and a bearing carrier inner race 5313. Sealing
between the two bearing carrier races 5311 and 5313 is effected by
the shaft sealing ring 532. The sealing rings 533 (in the form of
polymeric o-rings) act as a seal between the bearing carrier inner
race 5313 and the drive shaft 51. The sealing rings 533 also ensure
a reliable fit between the two parts. A safety ring or clip 534
secures the bearing carrier inner race 5313 on the drive shaft 51
against any axial displacement. This may also be accomplished using
a step formed in the drive shaft 51. The flexible bellow 531 is
clamped to the power take off housing 59 and the external bearing
carrier race 5311 by clamps 5314 and 5315, respectively.
Alternatively, the antifriction bearings 5312 are lubricated with
engine oil. The oil is supplied from a first crankshaft main
bearing 1232 via hollow bores 1233 in the crankshaft 123. The oil
flows through the arcuate teeth 511 to the antifriction bearings
5312 and finally returns between the power take off housing 59 and
the connecting assembly 52 into the interior of the engine. With
this arrangement, a second flexible seal is provided in the event
the flexible bellow 531 fails.
The power take off assembly 50 further includes a gear assembly 54,
as shown in FIGS. 36 and 37. The gear assembly 54 includes a main
gear 541 secured to the crankshaft 123 for driving the balance
shaft 115, a chain gear 542 integrally connected to the main gear
541 for driving a cam control chain 55, and a large gear 543. It is
contemplated that the chain gear 542 may be a separate component
that is either force fit, fastened to or integrated into the
crankshaft 123. The large gear 543 includes at least a first gear
5432 for engagement with a starter 56 through intermediate gear
561, as shown in FIG. 37 A second gear 5431 may be secured to the
large gear 543 if the engine 2 is so equipped for driving a
supercharger 90, as described below and shown in FIG. 38 For
reducing the number of required parts for the engine family, a
single gear 543 having both gears 5431 and 5432 may be used in
either the blown or normally aspirated engines. It is also
contemplated that the large gear 543 is formed as a single gear
such that a portion of each tooth of the gear is used to drive the
supercharger and another portion is used to drive the starter.
Linking the intermediate gear 561 for the starter assembly 56 to
the crankshaft 123 through the gear 543 results in a reduction of
the engine profile. A thrust screw drive within the intermediate
gear 561 for the starter assembly 56 allows for an automatic
engagement of a drive pinion 562 with the first gear 5432 during
the starting procedure. The intermediate gear 561 moves the drive
pinion 562 into engagement with the first gear 5432 against the
bias of a return spring 563. At least one dampening spring 564 is
provided to absorb vibration. After the starters operation is
complete, the thrust screw drive disengages such that the return
spring 563 biases the drive pinion 562 out of engagement with the
first gear 5432. The drive pinion 562 is mounted to a pinion shaft
565 that is connected to the starter assembly 56 such that
rotational movement generated by the starter assembly 56 is
transferred to the drive pinion 562. The pinion shaft 565 is
slidably and rotatably received within a recess in the power take
off housing 59.
As illustrated in FIG. 36, a generator assembly 57 is also part of
the power take off assembly 50. The generator assembly 57 includes
a magnet wheel 571 connected to the gear assembly 54, as shown in
FIG. 36 using suitable fasteners. The generator assembly 57 is a
permanently excited 3-phase generator, in which permanent magnets
572, which are fastened to magnet wheel 571, rotate around a stator
573. The stator 573 is fixed to the inner side of the power take
off lid 59. The location and arrangement of the generator assembly
57 provides for easy encapsulation because of reduced wiring
requirements. The magnet wheel 571 rotates around the stationary
coils. This arrangement is advantageous because it eliminates the
need for rotating coil members and also in view of possible repair
work. Furthermore, it reduces the weight of the rotating masses.
Additionally, the magnet wheel 571 is constructed as an
extrusion-molded part.
The rotational speed of the crankshaft 123 is measured by an engine
or crankshaft speed sensor 58 located within the power take off
housing 59. A cup shaped actuator 544 is secured to the gear
assembly 54 between the large gear 543 and the magnet wheel 571 of
the generator assembly 57. The actuator 544 extends between the
gear 543 and wheel 571 and between the sensor 58 and the wheel 571,
as shown in FIG. 36. The actuator 544 includes a plurality of teeth
extending around the perimeter thereof. A predetermined number of
teeth are missing at predetermined locations along the perimeter.
The sensor 58 detects the absence of the teeth as the actuator 544
rotates. The speed of the crankshaft and engine speed can be
determined from this.
Alternatively, it is contemplated that the magnet wheel 571 may
include at least one conductor piece mounted therein. The conductor
piece triggers the crankshaft or engine speed sensor 58.
Instantaneous values of the crankshaft position can be received
therefrom and the angular speed (rotational speed) is then
calculated by the engine management system 200, described below.
The angular resolution is 10.degree., i.e. during rotation of the
crankshaft 123, after every 10.degree. of rotation, a pulse is sent
by the crankshaft position sensor to the control device. It is
contemplated that the present invention is not limited to an
angular resolution of 10.degree.; rather, angular resolutions
greater than and less than 10.degree. are considered to be well
within the scope of the present invention.
The arrangement of the components within the power take off housing
59 results in a more compact engine design. As described above, the
engine components are located on the power take off end. The power
take off housing 59 protects these elements from the marine
conditions in which the personal watercraft operates. Furthermore,
a common drive assembly connected to the crankshaft 123 is provided
to drive these components without the need for numerous belts and
other connections. Additional features and benefits of the power
take off assembly 50 will be described below in connection with the
description of the lubricating system 60, the blow-by ventilation
system 70, engine cooling system 80 and supercharger 90.
Lubricating System
The lubricating system 60 will now be described in greater detail
in connection with FIGS. 8, 11, 12, 14-16 and 32-35.
The engines 1 and 2 have a dry-sump lubricating system 60. The
lubrication system 60 includes the oil tank 11, described above and
shown in FIG. 8. The oil collected in the crank chambers 121
emerges therefrom via outlet openings 111 into a channel 112. The
oil then flows to the upper portion 113 of the oil tank 11 adjacent
the balance shaft 115. From there, the oil flows back by gravity to
the bottom of the oil tank 11, where the oil is collected and
stored.
From the oil tank 11, the oil is conveyed to an oil cooling
assembly 86, shown in FIGS. 23 and 25, by an oil pump 61, as shown
in FIGS. 25 and 33 through integrated channels in the lower
crankcase 12. The oil pump 61 is integrated into the power take off
housing 59 and is coaxially disposed and driven by the balance
shaft 115 via a connecting shaft 612. The connecting shaft 612 is
received within a suitable recess within the end of the balance
shaft 115 such that rotation movement of the balance shaft 115 is
transferred to the drive shaft 612. The oil pump 61 is preferably a
troichoid pump. It is preferred that the oil be sucked from the
bottom of the oil tank 11. Furthermore, it is also preferred that
the oil be removed from a more centrally located pickup position
within the tank 11, rather than the front or rear of the tank 11.
This is a preventative measure to avoid air entrapment in extreme
operating conditions (extreme acceleration and deceleration modes).
The oil cooling assembly 86 is designed as a plate-type cooler and
is fixed onto the cylinder block 10. To cool the engine, water is
used in a closed cooling system 80, described in greater detail
below.
From the oil cooling assembly 86, the oil is conveyed to the oil
filter unit 62, as shown in FIGS. 32 and 34 through integrated
channels in the lower crankcase 12. The oil filter unit 62 has an
oil filter casing 621 that is integrated to the power take off
housing 59. The oil filter unit 62 is closed at one end by a
removable oil filter cover 622. Located within the oil filter
casing 621 is an annular oil filter 623 and a valve rod 624. One
end of the valve rod 624 is connected with the oil filter cover
622. The valve rod 624 is secured to the cover by a suitable
fastener. The valve rod 624 acts as a fastener to secure the cover
622 to the filter casing 621. The other end of the valve rod 624
extends into a drainage opening 625. When the valve rod 624 is
pulled out of the drainage opening 625, the oil which has remained
in the filter casing 621 can automatically drain through the
drainage opening 625. Alternatively, the oil filter cover 622 may
be configured as a screw lid.
Unlike conventional oil filter units where the overflow valve is
integrated in the upper region of the filter cover 622, the oil
filter unit 62 includes an external overflow valve 626 and a bypass
duct 627. In the event that the oil filter unit 62 is clogged, a
direct connection is formed between an inlet channel 628 and an
outlet channel 629 of the oil filter unit 62. This arrangement has
the advantage that the oil does not flow around a dirty oil filter.
Thus, no dirt particles can contaminate the oil circuit.
The filtered oil is then supplied to the engine 1 or 2 for
lubricating the various components through the main oil gallery in
the upper crankcase 13 of the crankcase 10, as illustrated in the
oil circuit in FIGS. 8 and 11.
One aspect of the lubricating system 60 relates to the return of
the oil from the crank chambers 121 in the upper crankcase 12 into
the integrated oil tank 11. The oil is pushed out of the crankcase.
This is effected by a differential pressure acting between the
crank chambers 121 and the oil tank 11 and the induction system,
respectively. This differential pressure is a result of the
pressure pulses caused by the pistons 1241 in the crank chambers
121. It is also partially due to a consequence of a "Blow-By"
effect, which refers to cylinder pressure losses. The piston 1241
does not provide a 100% sealing on the cylinder wall, so part of
the combustion gas caused during combustion leaks past the cylinder
downwardly into the lower crankcase 12. This so-called blow-by gas
creates additional pressure in the crank chambers 121 below the
pistons 1241 and is dependent on the load and the rotational speed
of the engine. However, on account of the above-mentioned blow-by
effect, the overall effect results in a pressure that is always
above the pressure between the air box and the throttle body. The
return of the blow-by gas is described in greater detail below in
connection with the blow-by ventilation system 70.
The rotational movement of the crankshaft 123 is also utilized to
carry oil to the outlet openings 111, and here two effects are to
be found. First, by the direct contact of the crank webs 1231 with
the oil, in case of direct wetting, there occurs an entrainment
effect as a consequence of the shearing forces. Second, with
smaller amounts of oil in the crank chambers 121, if there is no
direct contact between crank web 1231 and oil, gas forces will
occur which likewise drive the oil to the respective outlet
openings 111. At the base of the crank chambers 121, in the
vicinity of the outlet openings 111, stripper edges may be arranged
which strip the oil from the crank webs 1231.
To enable an optimum utilization of the above-described effect for
the oil return, the three crank chambers 121 (discussed above) in
the crankcase 12 are hermetically separated from each other, and
each crank chamber 121 is equipped with a separate outlet opening
111 for the oil. Thus, the pressure in one chamber is not affected
by the pressure in the other chambers. The cross-sections of the
channel system for the oil return following the outlet openings 111
are dimensioned suitably (i.e. not too large) so as to ensure the
conveyance of the oil back to the oil tank 11 on account of the
differential pressure, without the risk of a pressure equalization
between oil tank 11 and crankcase 12. Alternatively, the channels
can also unify, so that one single channel 112 leads to the oil
tank 11. The arrangement should be designed such that no oil
"shortcircuit" and no pressure balance will occur between the
individual crank chambers 121, i.e. oil must not be permitted to
flow directly from one crank chamber 121 into another chamber.
The return channels 112 for the oil return from the three
hermetically closed crank chambers 121 to the oil tank 11 may be
realized by channels cast into the lower crankcase 12 which enter
the oil tank 11 adjacent the union between the upper crankcase 13
and the lower crankcase 12. Alternately, they may be realized by
separate ducts, in particular hoses or tubes. As such, normally
hoses are only used in connection with external oil tanks. In the
present "in-case oil tank," hoses can be avoided. To prevent an
undesired flow-back of oil from the oil tank 11 to the crank
chambers 12 and--in consequence--a flooding of the crank chambers
in extreme inclined positions or in flip-over position of the
personal watercraft 5, non-return valves (not illustrated) may be
installed in the channels 112.
To remove the lubricating oil which has collected in the region
close to the bottom of the crank case 12 adjacent the bottom of the
power take off housing 59, a separate suction pump 71 is provided.
Like the oil pump 61, the suction pump 71 is coaxially arranged
along and driven by the balance shaft 115. The pump 71 is
preferably a troichoid pump. The pump 71 is located on an opposite
end of the balance shaft 115 when compared to the pump 61. The oil
is conveyed from the bottom of the power take off housing 59
through a duct 126 cast into the lower crankcase 12 to the suction
pump 71. Alternatively, it is contemplated that the blow-by gas
created in the crank chamber 121 adjacent the power take off
housing 59 is fed into the power take off housing 59 to provide
pressure to remove the oil from the bottom of the power take off
housing 59 near the bottom of the crank case.
The oil collected in the bottom of each crank chamber 121 exits
through the opening 111. The oil is then driven through the channel
112 back to the oil tank 11 by the blow-by gas pressure. The oil
collected inside the power take off housing 59 is removed by a
suction pump 71 or other suitable pumping assembly. The oil flows
through a channel 126, shown in FIGS. 11, 41 and 49, again
integrated into the lower crankcase 12 from the power take off side
to the opposite side, where the suction pump 71 is mounted, as
shown in FIGS. 40 and 41. The oil passes through an oil sieve 72
before it enters the suction pump 71 and is finally conveyed back
through a U-shaped channel 711 to the oil tank 11, as shown in
FIGS. 11, and 40. It is contemplated that the channel 711 is
integrated in the housing of the suction pump 71.
Regarding the oil circuit, it is added that cooling and lubrication
of the pistons 1241 and liners are effected by aid of spraying
nozzles 64 at the lower side of the piston 1241, as shown in FIG.
8. Oil is supplied to the nozzles 64 from the main oil gallery 65.
The spray nozzle 64 is positioned such that the jet reaches the
piston lower side not only in the lower dead center position
illustrated, but also in the upper dead center position.
FIGS. 8 and 35 illustrate one possible oil channel system 63 in the
region of the cylinder head housing 20 by way of a schematic 3D
representation. Other systems are contemplated to be well within
the scope of the present invention. The oil is conveyed to the
cylinder head housing 20 through at least one ascending duct 631 in
the upper crankcase 13. The ascendind duct 631 is connected to the
main oil gallery 65. The oil enters cylinder head housing 20 from
the ascending duct 631 through a transverse bore 632. In the
ascending duct 631, a throttle 6311 is installed which restricts
the amount of oil flowing therethrough. In addition, a check valve
6312 is disposed in the ascending duct 631, which blocks the oil
conduit as soon as the engine 1 or 2 is stopped. As such, a certain
amount of oil can be stored in the channels in the cylinder head
housing 20. This stored oil is particularly useful during a cold
start since lubrication can be initiated rapidly therewith and
provided to the valve train sooner to prevent damage to the valve
train.
Connecting bores 633 branch off of the transverse bore 632 and
connect the latter with the bores 634. The bores 634 also receive
the cylinder head fastening screws. The oil rises upwardly in the
annular gap between the cylinder head screw and the corresponding
bores 634. The oil then enters into a V-shaped channel section 635
formed by two obliquely downwardly directed bores 6351 and 6352.
From the ascending branch 6352 of the V-shaped channel section 635,
the oil directly enters into the interior of the hollow rocker arm
support axle 28. From there, the oil is directed to the bearing
places of the roker arm assemblies 25 and 26 via the radial
openings 282, as shown in FIG. 14. Also, the oil is admitted to the
operating assemblies 253 and 263. It is contemplated that other
channel systems and arrangements are well within the scope of the
present invention provided the channel systems conduct lubricant
from the main oil gallery 65 to the support axle 28.
Lubricant is supplied to the camshaft 29 via bearing bracket 293,
described above, through bore 636.
Below the camshaft 29, the oil ma y accumulate in a small basin in
which the lobes 291 and 292 of the camshaft 29 may be immersed for
lubricating purposes. The lubricant within the cylinder head
housing 20 collects in a depression under the camshaft 29 adjacent
the cylinder closest to the power take off assembly 50. The oil
from the other cylinders within the cylinder head flows to the
depression through passageways 295, which interconnect the areas in
the cylinder head adjacent the other cylinders . The oil exits the
cylinder head housing 20 through an inclined passageway into the
control chain chamber 202 where it flows into the power take off
assembly 50. This lubricant contributes to the lubrication of the
gears and supercharger 90(if present) within the power take off
assembly 50.
Blow-By Ventilation System
The engines 1 and 2 are preferably equipped with a blow-by
ventilation system 70 for separating oil from the vented blow-by
gas. A preferred form of the blow-by ventilation system 70 is
illustrated in FIGS. 3, 4, 11, 40, 41 and 46.
The blow-by gas originating from the combustion chambers 124 due to
leakage between the pistons 1241 and cylinder liners first
accumulates in the (sealed) crank chambers 121 and from there it
flows together with the oil through the channels 112 to the oil
tank 11, where it accumulates and mixes in the upper portion 113 of
the oil tank 11 with any gas in the oil tank 11 from the power take
off assembly 50. From the oil tank 11, the gas mixture is then
conveyed through a channel 712 (in the housing of the suction pump
71 and the lid of the sieve 72), shown in FIG. 40 to a shutoff and
pressure relieve valve 73, which is open in normal engine
operation. The pressure relief valve 73 includes a valve rod 731
that moves the valve 73 between open and closed positions by a
solenoid assembly 77. In the event that the solenoid assembly 77 is
not operational, the pressure relief valve 73 includes a spring
assembly 732 that permits the opening of the valve 73 in the event
of a build up of pressure within the tank 11.
The gas mixture from the oil tank 11 is split into two partial
flows: a first portion flows back to the cylinder head chamber
within the cylinder head housing 20 through a passageway 74, shown
in FIGS. 40 and 41. A second portion is vented tangentially into an
oil separator 75 designed as a cyclone. In the cyclone, the gas
mixture is separated from oil by centrifugal forces due to the
swirling of the gas/oil mixture in the cyclone. The cleaned gas
mixture leaves the cyclone through a central pipe 751. The cleaned
gas mixture then passes a second shutoff and pressure relief valve
76 and is finally conveyed to the air intake between the airbox and
the throttle body 411, where it merges with the fresh air drawn in
by the engine.
The shutoff and pressure relief valve 76 is also mounted on the
valve rod 731 and is also actuated by the solenoid 77. With this
arrangement, the valves 73 and 76 operate simultaneously. The
valves 73 and 76 are closed by drawback springs 732 and 761 when
the solenoid 77 is not activated and they are open when the
solenoid 77 is activated. With this arrangement, the engine is
sealed, preventing oil leaks when the engine is shut down. In
normal (upright vehicle) engine operation, the solenoid 77 is
activated and the valves 73 and 76 are opened respectively.
However, in the event of a roll-over of the vehicle, the valves are
closed instantly to prevent oil from entering the induction system
40 and/or the airbox and leaking into the environment. The closure
of valve 73 prevents oil from accumulating in the cylinder head
housing 20 in a roll-over event. This would cause a temporary lack
of oil in the oil tank 11, when the personal watercraft 5 has
returned to a normal upright position and could result in an
undersupply of lubricant to the engine, which may result in severe
damage to the engine 1 or 2. The valves 73 and 76 are also closed
when the engine is shut down.
A pressure sensor or sensor switch may be provided in the oil tank
11 or in the channel 712 to sense the pressure within the tank 11.
If the oil pressure exceeds a certain threshold value, the engine
management system 200 operates in an emergency mode (e.g. limp home
function). The engine management system operates the engine at a
reduced speed. The engine management system also interacts with
other onboard computers systems to notify the operator of the
engine malfunction. Additionally, the pressure sensor can be used
to detect oil leakage in the lubrication circuit.
The gas mixture enters the upper portion of the cyclone 75 through
the opening 755. As such, the gas mixture tangentially enters the
cyclone 75. Oil droplets within the gas mixture are thrust against
the inner wall of the cyclone 75 as a result of centrifugal forces
within the cyclone 75.
The separated oil then flows down the inner wall of the cyclone 75
towards opening 752; collects in the bottom of the cyclone 75; and
exits the cyclone 75 through an opening 752 into a channel 753
integrated in the sieve lid 721, and merges with the oil flow from
the power take off assembly 50 in front of the oil sieve 72, to be
conveyed back to the oil tank 11. Within the channel 753 there is
provided a throttle 754 which ensures that a sufficient height
negative pressure (vacuum) can build up in the suction port of the
suction pump 71, so that the power take off housing 50 is drained
reliably in all operating conditions. In a cold start condition
(when the oil is very viscous) the throttle 754 may even be closed
by an additional valve (not shown) especially at idling speed to
guarantee the aforesaid requirement.
An oil filler tube 78 is integrated to the cyclone 75. A cap 781 is
provided for closing the filler tube 78. Fresh oil flows down the
filler tube 78 into a channel 722 integrated in the sieve lid 721.
The oil enters a U-shaped duct through a port 715, shown in FIG.
40, in the housing of the suction pump, merges with the oil from
the power take off assembly 50 and is finally conveyed to the oil
tank 11.
In the preferred embodiment, the valves 73 and 76, the cyclone 75
and the oil filler tube 78 are assembled to form a single unit.
In accordance with the blow-by gas ventilation system 70 described
herein, a slight vacuum (underpressure, negative pressure,
subpressure) is generated in the interior in the power take off
assembly 50 and within the cylinder head housing 20. As a result,
no oil or contaminated blow-by gas can escape to the
environment.
Engine Cooling System
An engine cooling system 80 will now be described in connection
with FIGS. 25, 32 and 33. The engine cooling system 80 is a closed
system utilizing a coolant such as glycol, water or a mixture of
them. The present invention, however, is not limited to these
coolants; rather, it is contemplated that other cooling liquids are
considered to be well within the scope of the present invention.
The cooling circuit of the engine cooling system 80 is illustrated
in FIG. 25. The closed loop cooling system 80 cooperates with the
open loop cooling arrangement described above in connection with
the exhaust manifold 30 to effectively cool the engines 1 and
2.
The engine cooling system 80 includes a pump assembly 81 located on
one end of the engine 1 or 2, as shown in FIG. 32.
As illustrated in FIG. 33, the pump assembly 81 is arranged
externally of the power take off housing 59. The power take off
housing 59 and pump lid 611 together form the pump casing. It is
designed as a rotary pump and consists of an impeller 811 which is
located, screwed or attached onto the end of the connecting shaft
612, which projects from the power take off housing 59. The
connecting rod 612 also drives the oil pump 61. Impeller 811 is
driven by connecting rod 612. The connecting rod 612 also drives
the oil pump 61. The pump assembly 81 also includes a pump lid 812,
which is fastened to the power take off housing 59 and forms the
pump casing in cooperation therewith. The pump assembly 81 has a
one piece housing having an integrated thermostat.
As shown in FIG. 25, the coolant flows from the pump assembly 81
through a passageway 82 to the cylinder block of the upper
crankcase 13. The passageway 82 includes a main passageway 821 and
a by-pass passageway 822. The passageways 821 and 822 direct
coolant to the cooling passageway 125 in the cylinder block. The
coolant flows along the exterior of the cylinders 124, as shown in
FIG. 25. With this arrangement, the coolant travels in a generally
U-shaped manner along a side of the cylinders 124 adjacent the
intake manifold; around the end of the cylinder furthest from the
power take off assembly 50 and then along the side of the cylinders
adjacent the exhaust manifold in a direction back towards the power
take off assembly 50. At the same time, the coolant is directed in
an upward direction towards the cylinder head housing 20. The
by-pass passageway 822 reduces the load on the main passageway 821
and improves the flow pattern in the cooling passageway 125 at an
end portion of the cooling passageway 125 opposite the inlet. The
coolant from the by-pass passageway 822 mixtures with the coolant
in the coolant passageway 125 to reduce the temperature of the
coolant in the end portion of the cooling passageway 125.
Furthermore, the entry of coolant into the cooling passageway 125
from the by-pass passageway 822 improves the upward flow of coolant
into the cylinder head housing 20. It is preferred that the
passageways 821 and 822 are integrally formed in the power take off
housing 59 and crankcase 10. It, however, is contemplated that the
passageways may be hoses connecting the components to one
another.
From the upper crankcase 13, the coolant then passes upwardly to
the cylinder head housing 20 through bores 131 in a head gasket 130
positioned between the upper crankcase 13 and cylinder head housing
20, as schematically illustrated in FIG. 25. The bores 131 are
located on the exhaust manifold side of the gasket 130. These bores
130 act as throttles to adjust the flow of coolant into the
cylinder head housing 20. Additional small bores are located on the
intake manifold side of the gasket 130. These bores vent air
trapped within the passageway 125 into the cylinder head housing
20. The coolant first passes over the exhaust side of the cylinder
head toward the intake side of the cylinder head before exiting the
cylinder head housing 20 through a common passageway.
From the cylinder head housing 20, the coolant is then conveyed
through a hose to a thermostat 83 through an inlet passageway 817
located on the pump assembly 81, as shown in FIGS. 25 and 32. As
illustrated in FIG. 33, the thermostat 83 is directly mounted on
the pump lid 812. The thermostat 83 comprises a two-part thermostat
casing 831 and 832 including hose connections and a
temperature-sensitive valve 833, which automatically opens if a
predetermined temperature threshold value is exceeded. The coolant
then flows through outlet passage 816 to a heat exchanger 84 (shown
schematically in FIG. 25), where the coolant is cooled by
exchanging heat to the atmosphere. This can be in the form of a
cooling plate exposed to the body of water. The cooling plate may
be located in a lower portion of the hull of the personal
watercraft 5. The cooling plate is described in U.S. Provisional
Patent Application Ser. No. 60/160,819, filed Oct. 21, 1999
entitled "WATERCRAFT WITH CLOSED-LOOP HEAT EXCHANGER," and U.S.
patent application Ser. No. 09/691,129, filed Oct. 19, 2000
entitled "WATERCRAFT HAVING A CLOSED COOLANT CIRCULATING SYSTEM
WITH A HEAT EXCHANGER THAT CONSTITUTES AN EXTERIOR SURFACE OF THE
HULL" the specifications of which are incorporated herein
specifically by reference. The coolant is then returned to the pump
assembly 81 through an inlet 815.
The primary purpose of the cooling system 80 is to cool the engine
1 or 2 during operation. The operation of the cooling system 80 is
temporarily modified during engine start-up so that the engine
quickly reaches an optimal operating temperature. During initial
engine start-up, the thermostat 83 deactivates the heat exchanger
84. As such, the coolant is not cooled prior to reentry into the
pump assembly 81; rather, the coolant returns directly from the
inlet 817 into the coolant pump 81.
The cooling system 80 furthermore includes an oil cooling assembly
86. The oil cooling assembly 86 is connected to pump assembly 81
and thermostat 83. With this arrangement, a portion of the coolant
from the pump assembly 81 is directed to the oil cooling assembly
86 through passageway 861 to cool the engine oil. After passing
through the oil cooling assembly 86, the coolant returns to the
thermostat 83 via return passageway 862. The coolant from the
passageway 862 enters the thermostat housing in the vicinity of the
inlet 817. The oil cooling assembly 86 preferably is a plate-type
cooler and disposed on the side of the lower crankcase 12. The
coolant, which heats sooner than the oil, is used to heat the
engine oil during engine start-up.
The cooling system 80 further includes a temperature sensor 87,
which is linked to the engine management system, shown in FIGS. 25
and 42. As shown in FIG. 25, an expansion reservoir 88 is provided
in the return from the cylinder head housing 20 to the thermostat
83, as shown in FIG. 23. The expansion reservoir 88 adjusts for
expansion of the cooling fluid within the system 80. The expansion
reservoir 88 further a refill port 881 for refilling the system 80.
The reservoir 88 further provides a venting function for removing
air from the cooling system 80. In this manner, the interconnecting
duct between the reservoir 88 and the cylinder head housing 20 has
to be linked to the highest point in the cylinder head housing 20
to prevent the formation of an air barrier which could cause
overheating.
Supercharger Assembly
As discussed above, the engines in accordance with the present
invention may include a supercharger 90. The engine 2 having a
supercharger 90 is illustrated in FIGS. 6, 7, 30, 31 and 38. The
supercharger 90 is provided to increase the air intake and enhance
engine performance. The preassembled supercharger 90 is plugged in
a corresponding port 591, as shown in FIG. 33, in the power take
off housing 59 and sealed with sealing rings 592, as shown in FIG.
38. It is contemplated that a turbocharger may be used in
connection with the present invention. The supercharger, however,
provides improved operating characteristics when compared to the
turbocharger. Furthermore, the turbocharger produces additional
heat as compared to the supercharger, which places increased
demands on the cooling systems.
The supercharger 90 includes a cast housing 91, which is preferably
formed from a metal, however, it may be formed from a high strength
plastic or other suitable material. The housing 91 includes an
inlet portion 911. The inlet portion 911 is operatively connected
to the airbox (not shown). Air enters the supercharger 90 through
the inlet portion 911. Located within the housing 91 adjacent the
inlet portion 911 is an impeller 92, which operates to draw air
into the supercharger from the airbox. An air passageway 912
extends around the impeller 92 to collect the air compressed by the
impeller. The air passageway 912 is connected to the intake
manifold 41 through the throttle body 411. The housing 91 further
includes a mounting portion 913 that extends backward from the
inlet portion 911. The mounting portion 913 is received within the
port 591 in the power take off housing 59 and sealed with at least
one sealing assembly 592.
As shown in FIG. 38, a blower drive shaft 922 extends through the
mounting portion 913 and inlet portion 911. The blower drive shaft
922 is rotatably mounted within the housing 91 with at least one
bearing assembly 921. A drive pinion 93 is coupled to the blower
drive shaft 922. It is preferred that this be a non-positive
coupling. As such, the drive pinion 93 is non-positively connected
with the blower shaft 922 via an intermediate element 94 by a
biasing spring force, which is preferably supplied by a spring
assembly 95. The spring assembly 95 includes a plurality of cup
springs. Other spring assemblies and means for providing a
connection that can slip under high torque to prevent damage to the
impeller or other components, however, are considered to be well
within the scope of the present invention. The drive shaft 922
includes splines to prevent rotational movement of the intermediate
element 94 with respect to the drive shaft 922. The shaft 922
includes a lubrication passageway that delivers lubricant to the
drive pinion 93 to reduce wear. The lubrication passageway is
connected to the lubrication system. The connection between the
drive pinion 93 and the intermediate element 94 is formed as a
plane frictional surface. This unique connection assembly can
dampen the rotational and torsional vibrations transmitted by the
crankshaft 123.
The supercharger 90 is operatively coupled by the drive pinion 93
to the gear assembly 54 through gear 5431. The supercharger 90
preferably includes a cooling jacket connected to the open or
closed loop cooling system to cool and prevent failure of the
supercharger 90. The cooling of the supercharger 90 improves engine
performance.
In accordance with the present invention, the supercharger 90
preferably utilizes a low-cost rotary (radial or radial-axial)
blower. The present invention, however, is not limited to these
blowers; rather, it is contemplated that a positive displacement
blower (e.g. a Rootes or Wankel blower) may be employed.
Furthermore, the supercharger 90 may be used for separating a
certain water content from the intake air.
Control Tensioner
In accordance with the present invention, the engines 1 and 2 are
preferably equipped with a control tensioner for controlling the
tension within chain 55. The present invention, however, is not
limited for use with a chain; rather, it is contemplated that the
control tensioner can be used with other flexible linkages,
including but not limited to belts. A mechanical chain tensioner
100 is illustrated in FIG. 39. The tensioner 100 includes a driving
element 101. The driving element 101 preferably includes a spring
assembly. The spring assembly is preferably a rotationally active
helical pressure spring. The spring assembly 101 is rotationally
biased by aid of a thread cap 102. The spring includes a spring
ender 1011 that engages a slot 1021 in thread cap 102. The thread
cap 102 is externally screwed into a retainer 103. The spring
assembly 101 is received at one end in a blind hole bore of a
hollow adjustment element 104 which is screwed into a thread bore
of the retainer 103. The spring also includes a spring end 1012
that engages a slot 1042 in adjustment element 104. The overlapping
thread engagement of adjustment element 104 with retainer 103 is
designed to be relatively long. As oil gets into this threaded
connection, it provides a small damping effect to the adjustment
element 104 due to vibrations of the cam chain. This small damping
effect is enhanced if the thread overlap is kept relatively long.
The external thread of the adjustment element 104 preferably
includes multiple threads and it is designed such that it is
borderline self-locking in the retainer 103. This design must take
into account the presence of oil between the threads, which reduces
friction, when determining the necessary inclination of the
threads. If the inclination is too small (very self locking), a
strong spring force is required to overcome the locking action of
the threads. It is desirable to avoid unnecessary tension on the
chain to avoid wear and decreases in the lifetime of the chain. The
self tensioning action is effected by the interaction of the chain
vibration and the borderline self locking of the threads. That is,
it will maintain its extended position under normal loads but can
retract a distance under high loads to prevent damage to the cam
chain. For instance, if automatic adjustment occurs when the engine
is cold, upon reaching operation temperature, the aluminum cylinder
and head have expanded more than the steel cam chain and can create
too high of a tension in the chain. The borderline self locking
feature allows the plunger to retract slightly before chain tension
becomes so high as to damage the chain. The adjustment element 104
is rotationally driven by the spring assembly 101 if the tension of
the chain 55 slackens and is axially outwardly displaced. The
adjustment element 104 acts via a balancing arcuate intermediate
piece 105 on a tensioning rail 106. The chain tensioner 100 enables
a later adjustment by aid of the combined biasing and fixing
element 102 if the chain 55 undergoes elongation.
The thread piece 102, the retainer 103 and adjustment element 104
preferably are made of synthetic material because of the smaller
thermal elongation encountered as compared to aluminum. The
adjustment element 104 includes a steel insert 1041 on one end to
reduce wear.
In accordance with the present invention, the engines 1 and 2
described herein are not limited to the mechanical chain tensioner
100; rather, other tensioner assemblies are contemplated to be well
within the scope of the present invention. For example, a hydraulic
tensioner may be used. The mechanical tensioner 100, however, has
numerous advantages over this hydraulic counterpart. First, the
mechanical tensioner 100 can be manufactured at a lower cost and
does not require a complicated oil supply.
Engine Control Unit
The operation of the engine 1 or 2 is controlled by an engine
management system 200, as shown in FIG. 42. The engine management
system 200 includes an electronic control unit 201 monitors and
controls the operation of various engine components including but
not limited to ignition, the fuel pump, the fuel injection
assembly, the air intake, engine cooling, engine speed, engine
lubrication, exhaust gas in the muffler in response to input from
various sensors and monitors located with the engines 1 and 2. It
is contemplated that the electronic control unit 201 may further
control functions, such as, e.g., realization of a departing lock,
realization of a start/stop control, and the identification of
authorized personal watercraft users. The electronic control unit
201 further communicates with the other computer systems on the
personal watercraft for the control of instruments, non engine
watercraft functions and service needs.
The engine management system 200 also controls the gas pump 203 in
the gas tank 204, which includes a coarse filter 2041 and a float
assembly 2042.
The gas pump 203 has an associated pressure regulator 2043, such
that a constant gas pressure is mechanically provided. From there,
a returnless fuel system 205 leads to the injection nozzles or
valves 434 seated on the fuel rail 431. These injection nozzles 434
inject the fuel in the form of jets in the air in the intake
passageway. The engine management system 200 controls the operation
of the nozzles 434 such that there is sequential injection, wherein
each cylinder has an individual injection (i.e., no group
injection). The injection amount is determined by the engine
control device 201 on the basis of the applied characteristic
fields by the pulse width, i.e. by the duration of the injection
time.
A returnless fuel system 205 prevents the fuel from heating due to
the engine heat, as could otherwise be the case with a fuel return
from the engine to the fuel tank.
The engine management system 200 also includes various sensors,
such as the temperature sensor 39 in the exhaust muffler, an air
temperature sensor 43 attached to the intake manifold 41 and a
water temperature sensor 87.
A knock sensor 206 senses at an early time the knocking critical
for the engine--which has a high specific performance level. The
knock sensor 206 includes a piezo quartz element, which measures
the solid-borne acoustic signals at the cylinder block and
transmits the corresponding signals to the electronic control unit
201. The latter has a detection software to detect a possible
knocking combustion and to cause a correction in a manner known per
se, by ignition angle displacement.
The sensors further include the crankshaft position sensor 207. A
corresponding rotary position sensor 208 is associated with the
camshaft. By aid of this camshaft sensor 208, it is recognized
whether the crankshaft is present in the angle range of 0 to
360.degree. or in the range of 360 to 720.degree., which is
possible via the camshaft because the latter rotates at half the
rotational speed of the crankshaft. For the sake of simplicity, the
camshaft sensor 208 is directly associated with the chain wheel 551
at the camshaft.
For load measurement, the actual load of the engine is calculated
by the intake manifold pressure measured by sensor 210 and engine
speed measured from the crankshaft 123 in the power take off
assembly 50. A throttle potentiometer 209 is used for corrections
and a limp home function. In the event the engine is operating in a
limp home function (e.g., broken intake air pressure sensor), the
engine control unit 201 communicates with another onboard computer
system to notify the operator via an instrument panel that the
engine is operating in a limp home function. A pressure sensor 210
is arranged in the suction pipe to sense the absolute pressure,
which is especially useful for the engine 2 containing the
supercharger assembly 90 and for all operation modes with slightly
opened or closed throttle valve. Thus, there is no direct air
amount or air mass measurement, but auxiliary parameters are used
therefor.
Finally, for the sake of completeness, various voltage checks
should be mentioned which are carried out by the electronic control
unit 201, e.g. for the supply voltage of the injection valves,
which is useful insofar as the board voltage on the personal
watercraft 5 may very well fluctuate.
It will be apparent to those skilled in the art that various
modifications and variations may be made without departing from the
scope of the present invention. Thus, it is intended that the
present invention covers the modifications and variations of the
invention, provided they come within the scope of the appended
claims and their equivalents.
* * * * *